Production of itaconic acid and related molecules from aromatic compounds

ABSTRACT

This disclosure provides a genetically-modified bacterium from the genus Pseudomonas that produces itaconate or trans-aconitate. The disclosure further provides methods for producing itaconate or trans-aconitate using a genetically-modified bacterium from the genus Pseudomonas.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority from U.S. Provisional Application No. 62/664,570, filed Apr. 30, 2018, the contents of which are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This disclosure was made with government support under a research project supported by Prime Contract No. DE-AC05-00OR22725 awarded by the U.S. Department of Energy. The government has certain rights in this invention.

INCORPORATION BY REFERENCE OF SEQUENCE LISTING

The Sequence Listing in the ASCII text file, named as 37129_SEQLISTING_ST25.txt of 187 KB, created on Apr. 23, 2019, and submitted to the United States Patent and Trademark Office via EFS-Web, is incorporated herein by reference.

BACKGROUND

Lignin is one of the most abundant polymers on earth, second only to cellulose. Its complex structure makes it highly resistant to microbial degradation. Consequently, lignin is the primary cause of recalcitrance of lignocellulosic feedstock, and the primary constituent of waste effluent from second-generation biofuel fermentation. The United States can generate 1.3 billion dry tons of lignocellulosic biomass annually without competing with food crops for land use, and hence potentially deliver an equivalent supply of 3.8 billion barrels of oils that can replace more than 50% of liquid transportation derived from fossil fuels. However, one major limitation is that lignocellulosic residuals (i.e., lignins) constituting about 30% of the total biomass content cannot be currently used for fermentation and are underused as a low-value heating source by biorefinery processes. Therefore, it is significant to develop enabling technologies for transformation of this underused biomass source into high-value chemicals, biofuels, and biomaterials.

Utilization of the effluent lignocellulose waste stream would improve the overall process efficiency of second-generation biofuel production because the additional product would offset operating costs. This would effectively decrease the cost of the ethanol or butanol products, making them more competitive with traditional fossil fuels. Valorization of this waste stream will decrease the cost of treatment for any producing industries. So research paradigms or commercial ventures need not retool their foundational goals or core business models to incorporate this process.

Second-generation biofuels are a renewable energy source produced from lignocellulosic biomass, and they are fully compatible with existing infrastructure. Biofuels are produced in large bioreactors using single-celled microorganisms to convert the biomass into ethanol, butanol, or other hydrocarbons via fermentation processes. These single-celled organisms are incapable of degrading lignin, and consequently, the lignocellulosic biomass is never fully converted into desired products. In addition, the lignin present in the biomass feedstock shields the cellulose and hemicellulose that the microorganisms utilize effectively preventing optimum yields even when lignin degradation is not considered. Thus, up to 30% dry weight of the feedstock remain as lignin-containing residuals and wastes after biofuel production. Beside biofuel productions, other industrial activities that use lignocellulosic feedstock (e.g., production of pulp or paper) produce important amounts of lignocellulosic wastes. The resulting lignin-enriched waste stream is toxic to many microbes and plants, which leads to complications in its disposal since it is considered as hazardous waste. For twenty years, main treatment of lignocellulosic waste consisted of burning such wastes or burying, both of which have huge impacts on the environment. Then interest for valorizing these wastes rapidly expended over the recent years, using them as combustible heating source, for conversion by pyrolysis into char, gas and oil and used in building composite material. However, all these treatments convert only up to 3% of the remaining lignin.

The current slate of demonstrated lignin-derived products is very small and limited to native carbon storage compounds and intermediates of aromatic catabolism. To increase the portfolio of products that can be made from lignin, other parts of metabolism will need to be targeted.

The TCA cycle is a source of many value-added chemicals including succinate and citrate, but it has not yet been harnessed for lignin valorization. Itaconic acid (and its salt, itaconate, which are used interchangeably herein) and trans-aconitic acid (and its salt, trans-aconitate, which are used interchangeably herein) are unsaturated dicarboxylic acids derived from the TCA cycle with industrial uses including as an acrylate alternative and for the production of plastics, latex and other polymers (da Cruz et al., 3 Biotech 8.3 (2018): 138). Itaconate has been produced from simple sugars since the 1950s (Kuenz, A. et al., Applied Microbiology, and Biotech. 102.9 (2018): 3901-3914), and its potential to functionally replace several petroleum-derived commodity chemicals was highlighted by its selection as one of the top bio-based platform chemicals in several reports, including a 2004 United States Department of Energy report (Werpy, T. et al, No. DOE/GO-102004-1992. National Renewable Energy Lab, Golden, Colo. (US), 2004). However, the high cost of sugars makes itaconate production expensive, limiting it to use as a specialty chemical. Using lignin, a cheap and abundant feedstock, for production would enable much broader industrial use of itaconate.

The saprophytic bacterium Pseudomonas putida KT2440 is a microbe of industrial interest due to its robust metabolism (Ebert, Birgitta E., et al., Appl. Environ. Microbiol. 77.18 (2011): 6597-6605) and tolerance to xenobiotics (Kieboom, J. et al., Journal of Biological Chemistry 273.1 (1998), 85-91; Fernández, M. et al., Microbial biotechnology 2.2 (2009): 287-294.; Inoue, A. et al., Nature 338.6212 (1989): 264). P. putida also has the ability to tolerate and catabolize a wide-range of aromatic compounds (Jiménez, J I. et al., Environmental microbiology 4.12 (2002): 824-841) which led to its recent use in upgrading depolymerized lignin into PHAs (Gong, T. et al., Microbial biotechnology 9.6 (2016): 792-800; Linger, Jeffrey G., et al., Metabolic engineering communications 3 (2016): 24-29) and cis, cis-muconic acid (Kohlstedt, M. et al., Metabolic engineering 47 (2018): 279-293; Linger, J G., et al., PNAS 111.33 (2014): 12013-12018), In P. putida, lignin-derived aromatics are funneled into the β-ketoadipate pathway, producing acetyl-CoA and succinate (FIG. 1A). This direct route to key TCA cycle intermediates suggests that high yields of TCA cycle-derived products such as itaconate should be possible from lignin.

Growth phase production of itaconate may be challenging because itaconate can disrupt bacterial growth via inhibition of enzymes in the glyoxylate shunt and citramalate cycle. An alternate approach is to use a two-stage process to decouple growth of the microbial catalyst from conversion of feedstocks to chemicals, which provides solutions to many problems present in growth-associated processes (e.g. product toxicity, slow catalyst growth) (Burg, Jonathan M., et al., Curr. Op. in Chem. Eng., 14 (2016): 121-136). Such processes often take advantage of the natural responses of microbes to various nutrient limitations (e.g., nitrogen, sulfur, phosphate) and environmental shifts (e.g., O₂ limitation, temperature shifts) that prevent microbial growth while maintaining the metabolic reactions of interest and can be coupled with dynamic metabolic control tools to entirely reroute metabolism.

While itaconate is a valuable biologically-derived platform chemical, it inhibits the growth of many bacteria—particularly during growth on C1-C3 compounds—by inhibiting isocitrate lysate (Michelucci, Alessandro, et al., PNAS, 110.19 (2013): 7820-7825), which has limited industrial production to a few fungal species with narrow substrate ranges (Kuenz, A. et al., App. Microbio. & Biotech., 102.9 (2018): 3901-3914; da Cruz, Juliana Cunha et al., Biotech 8.3 (2018): 138). The use of Pseudomonas putida as a platform for itaconate production would broaden the range of industrially-relevant feedstocks that could be upgraded to include lignocellulosic hydrolysates, lignin streams (Rodriguez et al. Acs Sustain Chem Eng 5, 8171-8180 (2017); Linger, J G., et al., PNAS, 111.33 (2014): 12013-12018), pyrolysis oil (Jayakody, L N., et al., Energy & Environ. Sci., 11.6 (2018): 1625-1638.), and more.

BRIEF SUMMARY OF THE DISCLOSURE

In one aspect, the disclosure provides a genetically-modified bacterium from the genus Pseudomonas that utilizes TCA cycle intermediates to produce itaconate and trans-aconitate.

In some embodiments, the genetically-modified bacterium from the genus Pseudomonas comprises an exogenous nucleic acid encoding an enzyme that uses cis-aconitate as a substrate.

In some embodiments, the enzyme that uses cis-aconitate as a substrate is a cis-aconitate decarboxylase enzyme. In some embodiments, the cis-aconitate decarboxylase enzyme is encoded by a codon-optimized variant of the cadA gene from Aspergillus terreus. In some embodiments, the expression of the cis-aconitate decarboxylase enzyme is dynamically regulated. In a specific embodiment, the dynamic regulation of the cis-aconitate decarboxylase enzyme is achieved by a nitrogen-responsive promoter.

In some embodiments, the enzyme that uses cis-aconitate as a substrate is a cis-aconitate isomerase. In some embodiments, the genetically-engineered bacterium further expresses a trans-aconitate decarboxylase. In some embodiments, the cis-aconitate isomerase is encoded by a codon-optimized variant of the adi1 gene, and the trans-aconitate decarboxylase is encoded by a codon-optimized variant of the tad1 gene.

In some embodiments, the endogenous phaC1 and phaC2 genes, which encode polyhydroxyalkanoates (PHA) synthases, are inactivated in the bacterium to prevent formation of a competing product (PHA).

In some embodiments, the genetically-engineered bacterium further expresses a heterologous citrate synthase enzyme. In a specific embodiment, the citrate synthase enzyme is encoded by a codon-optimized, mutant variant of the Escherichia coli gltA gene. Citrate synthase catalyzes the formation of citrate from oxaloacetate and acetyl-CoA (FIG. 1B). Many of these enzymes are allosterically inhibited by intermediates expected to accumulate during production of itaconate, such as citrate. In some embodiments, the mutant variant of gltA is immune to allosteric inhibition.

In some embodiments, the genetically-modified bacterium further expresses an itaconic acid efflux pump. In some embodiments, the itaconic acid efflux pump is encoded by the itp1 gene. In a specific embodiment, the itp1 gene is a codon-optimized variant of the gene.

In some embodiments, the levels of the isocitrate dehydrogenase enzymes in the bacterium is reduced compared to a non-genetically-modified bacterium. Without committing to one particular theory, this reduction in levels of isocitrate dehydrogenases is thought to allow accumulation of the itaconate precursor cis-aconitate. In some embodiments, the genetically-modified bacterium has reduced expression of icd and idh genes, which encode for isocitrate dehydrogenases.

In some embodiments, the genetically-modified bacterium expresses a heterologous cis-aconitate isomerase enzyme but does not express a trans-aconitate decarboxylase enzyme, thereby allowing trans-aconitate to accumulate.

In some embodiments, the genetically-modified bacterium further expresses a trans-aconitate efflux pump. In some embodiments, the aconitate efflux pump is encoded by a codon-optimized variant of the tbrB gene.

In some embodiments, the bacterium is selected from the group consisting of P. aeruginosa, P. alcaligenes, P. anguilliseptica, P. argentinensis, P. borborid, P. citronellolis, P. flavescens, P. mendocina, P. nitroreducens, P. oleovorans, P. pseudoalcaligenes, P. resinovorans, P. straminea, P. asplenii, P. aurantiaca, P. aureofaciens, P. chlororaphis, P. corrugate, P. fragi, P. lundensis, P. taetrolens, P. Antarctica, P. azotoformans, P. blatchfordae, P. brassicacearum, P. brenneri, P. cedrina, P. corrugate, P. fluorescens, P. gessardii, P. libanensis, P. mandelii, P. marginalis, P. mediterranea, P. meridiana, P. migulae, P. mucidolens, P. orientalis, P. panacis, P. protegens, P. proteolytica, P. rhodesiae, P. synxantha, P. thivervalensis, P. tolaasii, P. veronii, P. denitrificans, P. pertucinogena, P. putida group, P. cremoricolorata, P. entomophila, P. fulva, P. monteilii, P. mosselii, P. oryzihabitans, P. parafulva, P. plecoglossicida, P. putida, P. balearica, P. luteola, P. stutzeri, P. amygdali, P. avellanae, P. caricapapayae, P. cichorii, P. coronafaciens, P. ficuserectae, P. helianthin, P. meliae, P. savastanoi, P. syringae, P. tomato, P. viridiflava, P. abietaniphila, P. acidophila, P. agarici, P. alcaliphila, P. alkanolytica, P. amyloderamosa, P. asplenii, P. azotifigens, P. cannabina, P. coenobios, P. congelans, P. costantinii, P. cruciviae, P. delhiensis, P. excibis, P. extremorientalis, P. frederiksbergensis, P. fuscovaginae, P. gelidicola, P. grimontii, P. indica, P. jessenii, P. jinjuensis, P. kilonensis, P. knackmussii, P. koreensis, P. lini, P. lutea, P. moraviensis, P. otitidis, P. pachastrellae, P. palleroniana, P. papaveris, P. peli, P. perolens, P. poae, P. pohangensis, P. proegens, P. psychrophile, P. psychrotolerans, P. rathonis, P. reptilivora, P. resiniphila, P. rhizosphaerae, P. rubescens, P. salomonii, P. segitis, P. septica, P. simiae, P. suis, P. teessidea, P. thermotolerans, P. toyotomiensis, P. tremae, P. trivialis, P. turbinellae, P. tuticorinensis, P. umsongensis, P. vancouverensis, P. vranovensis, P. xanthomarina, P. taiwanensis.

Another aspect of the disclosure is directed to methods of producing itaconic acid or trans-aconitate from organic compounds in an aqueous solution using a genetically-modified bacterium from the genus Pseudomonas described above.

In some embodiments, the organic compound is selected from aromatic compounds, saccharides, organic acids, and alcohols. In some embodiments, the organic compound is a breakdown product of lignin produced during a lignin depolymerization process. In some embodiments, the organic compound is selected from the group consisting of aromatic compounds, glycerol, diacids, fatty acids, and benzoic acid. In some embodiments, the aqueous solution is a lignin depolymerization stream or derived from a lignin depolymerization stream. In some embodiments, the lignin depolymerization stream contains p-coumaric acid, ferulic acid, and saccharides.

BRIEF DESCRIPTION OF THE FIGURES

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

FIGS. 1A-1E. Two-stage production of itaconic acid from the lignin-derived aromatic p-coumaric acid. (A) Simplified p-coumaric acid assimilation and β-ketoadipate pathway in Pseudomonas putida KT2440. (B) Simplified tricarboxylic acid (TCA) cycle in Pseudomonas putida KT2440 with modified or heterologous steps indicated by colored arrows, and connecting metabolites outlined. For simplicity some steps are not included. The cis (red arrow) and trans (green arrow) pathways for itaconate acid are indicated with involved genes, cadA (cis) & tad1/adi1 (trans) adjacent to the reaction their gene products perform. Isocitrate dehydrogenase activity, provided by the icd & idh gene products, is indicated by a purple arrow. (C) Simplified PHA (polyhydroxyalkanoate) production pathway in P. putida KT2440. The PHA pathway, via fatty acid biosynthesis, competes with the TCA cycle for acetyl-CoA during nitrogen-limited conditions. (D) Production of itaconic acid from p-coumarate in shake flasks by P. putida strains constitutively expressing cadA under nitrogen-limited conditions. Strain name and their unique modifications are indicated above the charts. Cell density (OD₆₀₀, gray diamonds), residual p-coumaric acid (mM, blue circles), and produced itaconic acid (mM, yellow triangles) are indicated. Error bars indicate the standard deviation in three replicates. (E) Growth rates of P. putida strains containing icd & idh start codon mutations with or without constitutive cadA expression using p-coumarate as sole carbon source. Rates were determined by 48-well microtiter plate cultivation. Error bars indicate the standard deviation in three replicates.

FIGS. 2A-2B. Production of itaconate by (A) strain JE3221 expressing the cis-pathway gene cadA, and (B) JE3659 expressing the trans-pathway genes tad1 & adi1, from the lignin-derived aromatic compound p-coumarate in shake flasks. Cell density as measured by OD₆₀₀ (gray diamonds), residual p-coumarate (blue circles), and produced itaconate (yellow triangles) are indicated. Values represent the average of three replicate shake flasks, with error bars indicated the standard deviation in among the three samples.

FIGS. 3A-3D. Reducing flux through the TCA cycle improves itaconate yield and titer. Production of itaconate from p-coumarate in shake flasks. Strains JE3713 (A) and JE3715 (B) have the GTG start codon replacements for icd and idh, and utilize the cis- and trans-pathways for itaconate production, respectively. Strains JE3717 (C) and JE3719 (D) have the TTG start codon replacements for icd and idh, and utilize the cis- and trans-pathways for itaconate production, respectively. Cell density as measured by OD₆₀₀ (gray diamonds), residual p-coumarate (blue circles), and produced itaconate (yellow triangles) concentrations are indicated. Values represent the average of three replicate shake flasks, with error bars indicated the standard deviation in among the three samples.

FIG. 4. Production of trans-aconitate from lignin-derived aromatics by strain JE3899 in shake flasks. Cell density as measured by OD₆₀₀ (gray diamonds), residual p-coumarate (blue circles), and produced trans-aconitate (purple triangles) are indicated. Values represent the average of three replicate shake flasks.

FIGS. 5A-5B. Effect of reduced isocitrate dehydrogenase production on growth and itaconate production by Pseudomonas putida KT2440. (A) Microtiter plate growth assay of P. putida strains harboring wild-type (gray circle), moderately reduced (yellow triangle), or strongly reduced (blue diamond) isocitrate dehydrogenase activity with p-coumarate as sole carbon source. Growth curves displayed are the average of three technical replicates. (B) Two-stage production of itaconic acid from p-coumaric acid in the presence of excess nitrogen (20 mM NH₄) by engineered P. putida strain JE4307 (constitutive cadA, icd^(TTG) idh^(TTG)) in shake flasks. Cell density (OD₆₀₀, gray diamonds), residual p-coumaric acid (mM, blue circles), and produced itaconic acid (mM, yellow triangles) are indicated. Error bars indicate the standard deviation in three replicates.

FIGS. 6A-6B. mNeonGreen production by constitutive promoter (P_(tac)) in a nitrogen-biosensor strain. Representative growth curves for 96-well microtiter plate cultivations of candidate biosensor strain JE2113 (P_(urtA):T7 RNAP, lysY+) with integrated (constitutive) P_(tac) controlled mNeonGreen cassette. Strain was grown in either nitrogen-replete (A) or nitrogen-limited conditions (B). Cell density and mNeonGreen production, as measured by OD₆₀₀ (gray) and relative fluorescence units (RFU—green) respectively, were measured every 10 minutes.

FIGS. 7A-7E. Development of a nitrogen-limitation biosensor to enable two-stage bioproductions. (A) Diagram of biosensor design and utilization as a regulated signal amplifier for pathway and tool expression. (B-C) Representative growth curves for 96-well microtiter plate cultivations of candidate biosensor strains, biosensor variant indicated, with integrated PT7:mNeonGreen cassette in either nitrogen-replete (B) or nitrogen-limited (C) medium. Cell density and mNeonGreen production, as measured by OD₆₀₀ (gray) and relative fluorescence units (RFU—green) respectively, were measured every 10 minutes. Entry to stationary phase is indicated (red dotted line) for nitrogen-limited cultures. (D) Graph of mNeonGreen production by candidate biosensor sensor strains during exponential growth (light green) or stationary phase (dark green) in microtiter plate cultivations. (E) Graph of mKate2 production by JE2113-derivatives with integrated PT7-variant:mKate2 cassettes during exponential growth (light pink) or stationary phase (dark pink) in plate reader cultivations. (d-e) Error bars indicate the standard deviation in at least 3 replicates.

FIGS. 8A-8E. Biosensor-controlled expression of itaconate production pathways enables high yield production from lignin and model aromatic substrates. (A, C) Production of itaconic acid from p-coumarate in shake flasks by strains utilizing dynamically-regulated (A) cadA (cis-pathway) or (C) tad1/adi1 (trans-pathway) under nitrogen-limited conditions. Strain name and their unique modifications are indicated above the charts. Cell density (OD600, gray diamonds), p-coumaric acid (mM, blue circles), and itaconic acid (mM, yellow triangles) are indicated. (B) The effect of cadA expression on growth of P. putida icd^(TTG) idh^(TTG) strains in 48-well microtiter plate assays with p-coumarate as sole carbon source. (D) Molar yield of engineered strains from shake flask experiments with 20 mM p-coumarate as sole carbon source. Overall yield (yellow) and production phase yield (green) are indicated. Production phase was defined as 24 hr to 96 hr time points. (E) Consumption of detected aromatic monomers and production of itaconic acid from depolymerized lignin containing either 2 mM or 3 mM supplemented NH₄Cl in shake flask cultivations with JE3715. (A-E) Error bars indicate the standard deviation in three replicates with the exception of the error bar for the 48 hr, 3 mM supplemented NH₄Cl where the bar represents absolute error in two replicates.

DETAILED DESCRIPTION OF THE DISCLOSURE Definitions

As used herein, the term “about” refers to an approximately +/−10% variation from a given value.

The term “homolog” means a gene related to a second gene by descent from a common ancestral DNA sequence, therefore, the corresponding polynucleotide/polypeptide has a certain degree of homology, that is to say sequence identity (preferably at least 40%, more preferably at least 60%, even more preferably at least 65%, particularly preferred at least 66%, 68%, 70%, 75%, 80%, 86%, 88%, 90%, 92%, 95°, 97% or 99%). A “homolog” of a protein furthermore means that the function is equivalent to the function of the original protein.

The term “cellulose” (also “lignocellulose” or “cellulosic substrate”) refers to a structural material that comprises much of the mass of plants. Lignocellulose is composed mainly of carbohydrate polymers (cellulose, hemicelluloses) and an aromatic polymer (lignin).

As used herein, the term “fermentation” refers to the enzymatic and/or anaerobic breakdown of organic substances by microorganisms to produce simpler organic compounds such as alcohols. While fermentation may occur under anaerobic conditions, it is not intended that the term be solely limited to strict anaerobic conditions, as fermentation may also occur under aerobic (e.g., in the presence of oxygen) or microaerobic conditions.

The term “genetically engineered” (or “genetically modified”) refers to a microorganism comprising a manipulated genome or nucleic acids.

“Lignin”, as used herein, refers to a complex polymer composed of monolignol subunits, primarily syringyl (S), guaiacyl (G) and p-hydroxyphenyl (H) monolignols, derived from sinapyl, coniferyl and p-coumaryl alcohols, respectively. Differences in the ratio of monolignols, and differences in expression and/or activity of lignin biosynthetic anabolic enzymes, create considerable variability in lignin structures, which differ between species, within species, within different tissues of a single plant and even within a single plant cell.

General Description

Disclosed herein are a genetically-modified bacterium from the genus Pseudomonas that can produce itaconic acid or trans-aconitate and methods of producing itaconic acid or trans-aconitate using the disclosed genetically-modified bacterium.

Genetically-Modified Bacterium

In some embodiments, the present disclosure is directed to a genetically-modified bacterium from the genus Pseudomonas comprising an exogenous nucleic acid encoding an enzyme that uses cis-aconitate as a substrate. In some embodiments, the genetically-modified bacterium is selected from the group consisting of P. aeruginosa, P. alcaligenes, P. anguilliseptica, P. argentinensis, P. borborid, P. citronellolis, P. flavescens, P. mendocina, P. nitroreducens, P. oleovorans, P. pseudoalcaligenes, P. resinovorans, P. straminea, P. asplenii, P. aurantiaca, P. aureofaciens, P. chlororaphis, P. corrugate, P. fragi, P. lundensis, P. taetrolens, P. Antarctica, P. azotoformans, P. blatchfordae, P. brassicacearum, P. brenneri, P. cedrina, P. corrugate, P. fluorescens, P. gessardii, P. libanensis, P. mandelii, P. marginalis, P. mediterranea, P. meridiana, P. migulae, P. mucidolens, P. orientalis, P. panacis, P. protegens, P. proteolytica, P. rhodesiae, P. synxantha, P. thivervalensis, P. tolaasii, P. veronii, P. denitrificans, P. pertucinogena, P. putida group, P. cremoricolorata, P. entomophila, P. fulva, P. monteilii, P. mosselii, P. oryzihabitans, P. parafulva, P. plecoglossicida, P. putida, P. balearica, P. luteola, P. stutzeri, P. amygdali, P. avellanae, P. caricapapayae, P. cichorii, P. coronafaciens, P. ficuserectae, P. helianthin, P. meliae, P. savastanoi, P. syringae, P. tomato, P. viridiflava, P. abietaniphila, P. acidophila, P. agarici, P. alcaliphila, P. alkanolytica, P. amyloderamosa, P. asplenii, P. azotifigens, P. cannabina, P. coenobios, P. congelans, P. costantinii, P. cruciviae, P. delhiensis, P. excibis, P. extremorientalis, P. frederiksbergensis, P. fuscovaginae, P. gelidicola, P. grimontii, P. indica, P. jessenii, P. jinjuensis, P. kilonensis, P. knackmussii, P. koreensis, P. lini, P. lutea, P. moraviensis, P. otitidis, P. pachastrellae, P. palleroniana, P. papaveris, P. peli, P. perolens, P. poae, P. pohangensis, P. protegens, P. psychrophile, P. psychrotolerans, P. rathonis, P. reptilivora, P. resiniphila. P. rhizosphaerae, P. rubescens, P. salomonii, P. segitis, P. septica, P. simiae, P. suis, P. teessidea, P. thermotolerans, P. toyotomiensis, P. tremae, P. trivialis, P. turbinellae, P. tuticorinensis, P. umsongensis, P. vancouverensis, P. vranovensis, P. xanthomarina, P. taiwanensis. In a specific embodiment, the bacterium is of the species P. putida.

In some embodiments, the exogenous nucleic acid sequence is codon optimized for the specific Pseudomonas strain used. The term “codon-optimized” refers to nucleic acid molecules that are modified based on the codon usage of the host species (herein the specific Pseudomonas strain used), but without altering the polypeptide sequence encoded by the nucleic acid.

In some embodiments, the genetically-modified bacterium comprises an exogenous nucleic acid encoding a cis-aconitate decarboxylase (cad) enzyme. In a specific embodiment, the cad enzyme is encoded by the cad1 gene from Aspergillus terreus having a protein sequence as shown by SEQ ID NO: 108, or a homolog thereof. In some embodiments, the expression of the cad1 gene is dynamically regulated. In some embodiments, the dynamic regulation of cad expression comprises limiting the expression to production phase. In some embodiments, the dynamic regulation of cad1 expression is achieved by an orthogonal RNA polymerase intermediary. In a specific embodiment, the orthogonal RNA polymerase intermediary is T7pol with a nitrogen-sensitive promoter. In a specific embodiment, the nitrogen-sensitive promoter comprises a sequence selected from SEQ ID NOs: 85-89.

In some embodiments, the genetically-modified bacterium comprises an exogenous nucleic acid encoding an aconitate isomerase enzyme. In a specific embodiment, the aconitate isomerase enzyme is encoded by the adi1 gene from Ustilago maydis having a protein sequence as shown by SEQ ID NO: 110, or a homolog thereof. In some embodiments, the exogenous nucleic acid further encodes a trans-aconitate decarboxylase enzyme. In a specific embodiment, the aconitate isomerase enzyme is encoded by the tad gene from Ustilago maydis having a protein sequence as shown by SEQ ID NO: 109, or a homolog thereof.

In some embodiments, the genetically-modified bacterium comprises an exogenous nucleic acid encoding a cis-aconitate decarboxylase (cad) enzyme, an exogenous nucleic acid encoding an aconitate isomerase, and an exogenous nucleic acid encoding a trans-aconitate decarboxylase as described above.

In some embodiments, a gene encoding for a poly-hydroxyalkonate synthase enzyme, or homolog thereof, is inactivated in the bacterium. In some embodiments, all poly-hydroxyalkonate synthase enzymes, or homologs thereof are inactivated in the bacterium. In a specific embodiment, the endogenous phaC1 gene and the endogenous phaC2 gene are inactivated in the bacterium.

In some embodiments, the inactivation of the poly-hydroxyalkonate synthase gene includes a deletion of the whole or a part of the gene such that no functional protein product is expressed (also known as gene knock out). The inactivation of a gene may include a deletion of the promoter or the coding region, in whole or in part, such that no functional protein product is expressed. In other embodiments, the inactivation of poly-hydroxyalkonate synthase includes introducing an inactivating mutation to the gene, such as an early STOP codon in the coding sequence of the gene, such that no functional protein product is expressed.

In some embodiments, gene inactivation is achieved using available gene targeting technologies in the art. Examples of gene targeting technologies include the Cre/Lox system (described in Kühn, R., & M. Torres, R., Transgenesis Techniques: Principles and Protocols, (2002), 175-204.), homologous recombination (described in Capecchi, Mario R., Science (1989), 244: 1288-1292), and TALENs (described in Sommer et al., Chromosome Research (2015), 23: 43-55, and Cermak et al., Nucleic Acids Research (2011): gkr218.).

In one embodiment, poly-hydroxyalkonate synthase inactivation is achieved by a CRISPR/Cas system. CRISPR-Cas and similar gene targeting systems are well known in the art with reagents and protocols readily available. Exemplary genome editing protocols are described in Jennifer Doudna, and Prashant Mali, “CRISPR-Cas: A Laboratory Manual” (2016) (CSHL Press, ISBN: 978-1-621821-30-4) and Ran, F. Ann, et al. Nature Protocols (2013), 8 (11): 2281-2308.

In some embodiments, the genetically-modified bacterium further comprises an exogenous nucleic acid encoding a citrate synthase. In a specific embodiment, the citrate synthase enzyme is encoded by the gltA gene from E coli, or a homolog thereof. In some embodiments, the exogenously-expressed citrate synthase enzyme is a mutant enzyme that is immune to allosteric inhibition by intermediates expected to accumulate during production of itaconate, such as citrate.

In some embodiments, the level of endogenous isocitrate dehydrogenase in the genetically-modified bacterium is reduced compared to a non-genetically modified bacterium. In some embodiments, the level of endogenous isocitrate dehydrogenase is reduced because transcription or translation efficiency, or stability of the isocitrate dehydrogenase mRNA is decreased. In a specific embodiment, the start codon of the endogenous isocitrate dehydrogenase gene is either “GTG” or “TTG” instead of “ATG.” In some embodiments, the isocitrate dehydrogenase gene promoter comprises a mutation that decreases transcription efficiency. In some embodiments, the ribosome binding site of the isocitrate dehydrogenase gene transcript comprises a mutation that decreases the translation efficiency of the mRNA. In some embodiments, the level of endogenous isocitrate dehydrogenase is reduced because of a reduction in isocitrate dehydrogenase protein stability. In some embodiments, the isocitrate dehydrogenase protein encoded by the isocitrate dehydrogenase gene comprises a protease recognition sequence which renders it more likely to be degraded by cellular proteases.

In some embodiments, the genetically-modified bacterium is grown on an organic compound. In some embodiments, the organic compound is lignin, or a breakdown product of lignin (e.g., p-coumaric acid, ferulic acid, and saccharides). In some embodiments, the organic compound is selected from aromatic compounds, saccharides, organic acids, and alcohols. In some embodiments, the organic compound is a saccharide, not limited to a saccharide that Pseudomonas species can natively consume (e.g., glucose) but also one that the Pseudomonas species have been engineered to consume (e.g., xylose and arabinose). In some embodiments, the organic compound is an aromatic compound, and the aromatic compound comprises coumarate, ferulate, or benzoate. In some embodiments, the organic compound is an organic acid, and the organic compound comprises diacids (e.g., succinic acid), or fatty acids (e.g., acetic acid and octanoic acid), In some embodiments, the organic compound is a waste product from the production of biodiesel. In a specific embodiment, the waste product from the production of biodiesel is glycerol.

In some embodiments, the genetically-engineered bacterium further comprises an exogenous nucleic acid encoding an itaconic acid efflux pump. In some embodiments, the itaconic acid efflux pump is encoded by an itp1 gene. In a specific embodiment, the exogenous nucleic acid encodes an itp1 protein from Ustilago maydis having the sequence as shown in SEQ) ID NO: 111, or a homolog thereof. In some embodiments, the nucleic acid is codon optimized.

In some embodiments, the genetically-engineered bacterium further comprises an exogenous nucleic acid encoding a trans-aconitate efflux pump. In some embodiments, the itaconic acid efflux pump is encoded by a tbrB gene. In a specific embodiment, the exogenous nucleic acid encodes a TbrB protein from Bacillus thuringiensus CT-43 having the sequence as shown in SEQ ID NO: 112, or a homolog thereof. In some embodiments, the nucleic acid is codon optimized.

Methods for Converting an Organic Compound to Itaconic Acid or Trans-Aconitate

Another aspect of the disclosure is directed to a method for converting an organic compound to itaconic acid or trans-aconitate, the method comprising inoculating an aqueous solution containing said organic compound with a genetically-modified bacterium from the genus Pseudomonas, wherein the bacterium comprises an exogenous nucleic acid encoding an enzyme that uses cis-aconitate as a substrate.

In some embodiments, the genetically-modified bacterium of the claimed method is grown on an organic compound. In some embodiments, the organic compound is lignin, or a breakdown product of lignin (e.g., p-coumaric acid, ferulic acid, and saccharides). In some embodiments, the organic compound is selected from aromatic compounds, saccharides, organic acids, and alcohols. In some embodiments, the organic compound is a saccharide, not limited to a saccharide that Pseudomonas species can natively consume (e.g., glucose) but also one that the Pseudomonas species have been engineered to consume (e.g., xylose and arabinose). In some embodiments, the organic compound is an aromatic compound, and the aromatic compound comprises coumarate, ferulate, or benzoate. In some embodiments, the organic compound is an organic acid, and the organic compound comprises diacids (e.g., succinic acid), or fatty acids (e.g., acetic acid and octanoic acid). In some embodiments, the organic compound is a waste product from the production of biodiesel. In a specific embodiment, the waste product from the production of biodiesel is glycerol.

In some embodiments, the genetically-modified bacterium of the claimed method is selected from the group consisting of P. aeruginosa, P. alcaligenes, P. anguilliseptica, P. argentinensis, P. borborid, P. citronellolis, P. flavescens, P. mendocina, P. nitroreducens, P. oleovorans, P. pseudoalcaligenes, P. resinovorans, P. straminea, P. asplenii, P. aurantiaca, P. aureofaciens, P. chlororaphis, P. corrugate, P. fragi, P. lundensis, P. taetrolens, P. Antarctica, P. azotoformans, P. blatchfordae, P. brassicacearum, P. brenneri, P. cedrina, P. corrugate, P. fluorescens, P. gessardii, P. libanensis, P. mandelii, P. marginalis, P. mediterranea, P. meridiana, P. migulae, P. mucidolens, P. orientalis, P. panacis, P. protegens, P. proteolytica, P. rhodesiae, P. synxantha, P. thivervalensis, P. tolaasii, P. veronii, P. denitrificans, P. pertucinogena, P. putida group, P. cremoricolorata, P. entomophila, P. fulva, P. monteilii, P. mosselii, P. oryzihabitans, P. parafulva, P. plecoglossicida, P. putida, P. balearica, P. luteola, P. stutzeri, P. amygdali, P. avellanae, P. caricapapayae, P. cichorii, P. coronafaciens, P. ficuserectae, P. helianthin, P. meliae, P. savastanoi, P. syringae, P. tomato, P. viridiflava, P. abietaniphila, P. acidophila, P. agarici, P. alcaliphila, P. alkanolytica, P. amyloderamosa, P. asplenii, P. azotifigens, P. cannabina, P. coenobios, P. congelans, P. costantinii, P. cruciviae, P. delhiensis, P. excibis, P. extremorientalis, P. frederiksbergensis, P. fuscovaginae, P. gelidicola, P. grimontii, P. indica, P. jessenii, P. jinjuensis, P. kilonensis, P. knackmussii, P. koreensis, P. lini, P. lutea, P. moraviensis, P. otitidis, P. pachastrellae, P. palleroniana, P. papaveris, P. peli, P. perolens, P. poae, P. pohangensis, P. protegens, P. psychrophile, P. psychrotolerans, P. rathonis, P. reptilivora, P. resiniphila. P. rhizosphaerae, P. rubescens, P. salomonii, P. segitis, P. septica, P. simiae, P. suis, P. teessidea, P. thermotolerans, P. toyotomiensis, P. tremae, P. trivialis, P. turbinellae, P. tuticorinensis, P. umsongensis, P. vancouverensis, P. vranovensis, P. xanthomarina, P. taiwanensis. In a specific embodiment, the bacterium is of the species P. putida.

In some embodiments, the exogenous nucleic acid sequence is codon optimized for the specific Pseudomonas strain used. The term “codon-optimized” refers to nucleic acid molecules that are modified based on the codon usage of the host species (herein the specific Pseudomonas strain used), but without altering the polypeptide sequence encoded by the nucleic acid.

In some embodiments, the genetically-modified bacterium of the claimed method comprises an exogenous nucleic acid encoding a cis-aconitate decarboxylase (cad) enzyme. In a specific embodiment, the cad enzyme is encoded by the cad1 gene from Aspergillus terreus having a protein sequence as shown by SEQ ID NO: 108, or a homolog thereof. In some embodiments, the expression of the cad/gene is dynamically regulated. In some embodiments, the dynamic regulation of cad1 expression comprises limiting the expression to production phase. In some embodiments, the dynamic regulation of cad1 expression is achieved by an orthogonal RNA polymerase intermediary. In a specific embodiment, the orthogonal RNA polymerase intermediary is T7pol with a nitrogen-sensitive promoter. In a specific embodiment, the nitrogen-sensitive promoter comprises a sequence selected from SEQ ID NOs: 85-89.

In some embodiments, the genetically-modified bacterium of the claimed method comprises an exogenous nucleic acid encoding an aconitate isomerase enzyme. In a specific embodiment, the aconitate isomerase enzyme is encoded by the adi1 gene from Ustilago maydis having a protein sequence as shown by SEQ ID NO: 110, or a homolog thereof. In some embodiments, the exogenous nucleic acid further encodes a trans-aconitate decarboxylase enzyme. In a specific embodiment, the aconitate isomerase enzyme is encoded by the tad1 gene from Ustilago maydis having a protein sequence as shown by SEQ ID NO: 109, or a homolog thereof.

In some embodiments, the genetically-modified bacterium of the claimed method comprises an exogenous nucleic acid encoding a cis-aconitate decarboxylase (cad) enzyme, an exogenous nucleic acid encoding an aconitate isomerase, and an exogenous nucleic acid encoding a trans-aconitate decarboxylase as described above.

In some embodiments, a gene encoding for a poly-hydroxyalkonate synthase enzyme, or homolog thereof, is inactivated in the bacterium. In some embodiments, all poly-hydroxyalkonate synthase enzymes, or homologs thereof, are inactivated in the bacterium. In a specific embodiment, the endogenous phaC1 gene and the endogenous phaC2 gene are inactivated in the bacterium.

In some embodiments, the inactivation of the poly-hydroxyalkonate synthase gene includes a deletion of the whole or a part of the gene such that no functional protein product is expressed (also known as gene knock out). The inactivation of a gene may include a deletion of the promoter or the coding region, in whole or in part, such that no functional protein product is expressed. In other embodiments, the inactivation of poly-hydroxyalkonate synthase includes introducing an inactivating mutation to the gene, such as an early STOP codon in the coding sequence of the gene, such that no functional protein product is expressed.

In some embodiments, gene inactivation is achieved using available gene targeting technologies in the art. Examples of gene targeting technologies include the Cre/Lox system (described in Kühn, R., & M. Torres, R., Transgenesis Techniques: Principles and Protocols, (2002), 175-204.), homologous recombination (described in Capecchi, Mario R., Science (1989), 244: 1288-1292), and TALENs (described in Sommer et al., Chromosome Research (2015), 23: 43-55, and Cermak et al., Nucleic Acids Research (2011): gkr218.).

In one embodiment, poly-hydroxyalkonate synthase inactivation is achieved by a CRISPR/Cas system. CRISPR-Cas and similar gene targeting systems are well known in the art with reagents and protocols readily available. Exemplary genome editing protocols are described in Jennifer Doudna, and Prashant Mali, “CRISPR-Cas: A Laboratory Manual” (2016) (CSHL Press, ISBN: 978-1-621821-30-4) and Ran, F. Ann, et al. Nature Protocols (2013), 8 (1): 2281-2308, which are incorporated in their entireties.

In some embodiments, the genetically-modified bacterium further comprises an exogenous nucleic acid encoding an exogenous nucleic acid encoding a citrate synthase. In a specific embodiment, the citrate synthase enzyme is encoded by the gltA gene from E. coli, or a homolog thereof. In some embodiments, the exogenously-expressed citrate synthase enzyme is a mutant enzyme that is immune to allosteric inhibition by intermediates expected to accumulate during production of itaconate, such as citrate.

In some embodiments, the level of endogenous isocitrate dehydrogenase in the genetically-modified bacterium is reduced compared to a non-genetically modified bacterium. In some embodiments, the level of endogenous isocitrate dehydrogenase is reduced because transcription or translation efficiency, or stability of the isocitrate dehydrogenase mRNA is decreased. In a specific embodiment, the start codon of the endogenous isocitrate dehydrogenase gene is either “GTG” or “TTG” instead of “ATG.” In some embodiments, the isocitrate dehydrogenase gene promoter comprises a mutation that decreases transcription efficiency. In some embodiments, the ribosome binding site of the isocitrate dehydrogenase gene transcript comprises a mutation that decreases the translation efficiency of the mRNA. In some embodiments, the level of endogenous isocitrate dehydrogenase is reduced because of a reduction in isocitrate dehydrogenase protein stability. In some embodiments, the isocitrate dehydrogenase protein encoded by the isocitrate dehydrogenase gene comprises a protease recognition sequence which renders it more likely to be degraded by cellular proteases.

In some embodiments, the genetically-engineered bacterium further comprises an exogenous nucleic acid encoding an itaconic acid efflux pump. In some embodiments, the itaconic acid efflux pump is encoded by an itp1 gene. In a specific embodiment, the exogenous nucleic acid encodes an itp1 protein from Ustilago maydis having the sequence as shown in SEQ ID NO: 111, or a homolog thereof. In some embodiments, the nucleic acid is codon optimized.

In some embodiments, the genetically-engineered bacterium further comprises an exogenous nucleic acid encoding a trans-aconitate efflux pump. In some embodiments, the itaconic acid efflux pump is encoded by a ThrB gene. In a specific embodiment, the exogenous nucleic acid encodes a TbrB protein from Bacillus thuringiensus CT-43 having the sequence as shown in SEQ ID NO: 112, or a homolog thereof. In some embodiments, the nucleic acid is codon optimized.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.

The present disclosure is further illustrated by the following non-limiting examples.

EXAMPLES Example 1: Materials and Methods General Culture Conditions and Media

TABLE 1 The bacterial strains used in this study: Strains Relevant Genotype NEB 5- Escherichia coli F′ proA⁺B⁺ lacI^(q) Δ(lacZ)M15 zzf::Tn10 (Tet^(R))/ alpha F′Iq fhuA2Δ(argF-lacZ)U169 phoA glnV44 ΦP80Δ ′lacZ)M15 gyrA96 recA1 relA1 endA1 thi-1 hsdR17 Epi400 Escherichia coli F⁻ mcrA Δ(mrr-hsdRMS-mcrBC) Φ80dlacZΔM15 ΔlacX74 recA1 endA1 araD139 Δ(ara, leu)7697 galU galK λ⁻ rpsL (Str^(R)) nupG trfA tonA pcnB4 dhfr QP15 Escherichia coli F′ proA⁺B⁺ lacI^(q) Δ(lacZ)M15 zzf::Tn10 (Tet^(R))/ mcrA Δ(mrr-hsdRMS-mcrBC) Φ80dlacZΔM15 ΔlacX74 recA1 endA1 araD139 Δ(ara, leu)7697 galU galK λ⁻ rpsL (Str^(R)) nupG trfA tonA pcnB4 dhfr BL21 (DE3) Escherichia coli F−, ompT, hsdS_(B) (r_(B−), m_(B−)), dcm, gal, λ(DE3), pLysS pLysS, Cm^(r). JE90 Pseudomonas putida KT2440 ΔhsdR::Bxb1int-attB JE2113 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::lysY:PurtA:T7_RNAP JE3128 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:PT7:cadA:attR ΔampC::lysY:PurtA:T7_RNAP JE3215 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 JE3219 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:PT7:mNeonGreen:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 JE1622 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::P_(PP2685):T7pol JE1626 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::P_(PP2688):T7pol JE1629 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::P_(urtA):T7pol JE1633 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::P_(glnK):T7pol JE1651 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:P_(T7):mNeonGreen:attR ΔampC::P_(PP2685):T7pol JE1652 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:P_(T7):mNeonGreen:attR ΔampC::P_(PP2688):T7pol JE1653 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:P_(T7):mNeonGreen:attR ΔampC::P_(urtA):T7pol JE1654 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:P_(T7):mNeonGreen:attR ΔampC::P_(glnK):T7pol JE1655 P. putida KT2440 ΔhsdR:Bxb1int- attL:nptII:mNeonGreen(promoterless):attR JE1657 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:P_(T7):mNeonGreen:attR JE2113 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::lysY:P_(urtA):T7_RNAP JE2211 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:P_(tac):mNeonGreen:attR ΔampC::lysY:P_(urtA):T7pol JE2212 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:P_(T7):mNeonGreen:attR ΔampC::lysY:P_(urtA):T7pol JE3215 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::lysY:P_(urtA):T7pol ΔphaC₁ZC₂ JE3221 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:PT7:cadA:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 JE3659 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:PT7:tad1:adi1:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 JE3674 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 icdGTG:idhGTG JE3681 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 icdTTG:idhTTG JE3712 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:PT7:mNeonGreen:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 icdGYG:idhGYG JE3713 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:PT7:cadA:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 icdGTG:idhGTG JE3715 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:PT7:tad1:adi1:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 icdGTG:idhGYG JE3716 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:PT7:mNeonGreen:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 icdTTG:idhTTG JE3717 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:PT7:cadA:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 icdTTG:idhTTG JE3719 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:PT7:tad1:adi1:attR ΔampC::lysY:PurtA:T7_RNAP ΔphaC1ZC2 icdTTG:idhTTG JE3899 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:PT7:adi1:attR ΔampC::lysY:PurtA:T7_RNAP AphaC1ZC2 icdTTG:idhTTG JE3729 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:P_(T7):mKate2:attR ΔampC::lysY:P_(urtA):T7pol JE3730 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:P_(T7) _(—) _(C4):mKate2:attR ΔampC::lysY:P_(urtA):T7pol JE3732 P. putida KT2440 ΔhsdR::Bxb1int- attL:nptII:P_(T7) _(—) _(H10):mKate2:attR ΔampC::lysY:P_(urtA):T7pol JE3734 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:P_(T7) _(—) _(H9):mKate:attR ΔampC::lysY:P_(urtA):T7pol JE3736 P. putida KT2440 ΔhsdR:Bxb1int-attL:nptII:P_(T7) _(—) _(G6):mKate2:attR ΔampC::lysY:P_(urtA):T7pol JE3738 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:P_(tac):mKate2:attR ΔampC::lysY:P_(urtA):T7pol JE669 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔphaC₁ZC₂ JE4296 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔphaC₁ZC₂ icd^(GTG):idh^(GTG) JE4273 P. putida KT2440 ΔhsdR::Bxb1int-attB ΔphaC₁ZC₂icd^(TTG):idh^(TTG) JE4305 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:P_(tac):cadA:attR JE4306 P. putida KT2440 ΔhsdR::Bxb1int-attL:nptII:P_(tac):cadA:attR ΔphaC₁ZC₂ P. putida KT2440 ΔhsdR::Bxb1int-attL:nptH:P_(rac).cafiM.att7? JE4307 ΔphaC₁ZC₂icd^(TTG):idh^(TTG)

TABLE 2 Plasmids used in this study: Plasmids pJE382 pUC origin, nptII, sacB, mcs-lacZa pK18mobsacB pUC origin, nptII, sacB, Plac:mcs-lacZa pLysS p15A origin, cat, lysS pJE990 pUC origin, nptII, mNeonGreen (promoterless) pJE387 pK18mobsacB ΔampC pJE473 pJE382 ΔphaC1ZC2 pJE1031 pJE382 ΔampC pJE1037 pJE382 ΔampC::PurtA:T7_RNAP pJE1040 pJE990 PT7:mNeonGreen pJE1180 pJE382 ΔampC::lysY:PglnK:T7_RNAP pJE1380 pJE990 PT7:cadA pJE1443 pJE990 PT7:tad1:adi1 pJE1444 pJE382 icdGTG:idhGTG pJE1445 pJE382 icdTTG.idhTTG pJE1383 pJE990 PT7:adi1

Routine cultivation of Escherichia coli for plasmid construction and maintenance was performed at 37° C. using LB (Miller) medium supplemented with 50 μg/mL kanamycin sulfate and 15 g/L agar (for solid medium). All Pseudomonas putida cultures were incubated at 30° C., with shaking at 250 rpm for liquid cultures. LB (Miller) was used for routine Pseudomonas putida strain maintenance, competent cell preparations, and starter cultures. For itaconate production assay starter cultures, the media was supplemented with 50 μg/mL kanamycin sulfate.

Modified M9 medium (M9*) with variable amounts of NH₄Cl was utilized for shake flask experiments, growth rate assays, and fluorescent reporter assays (47.8 mM Na2HPO4, 22 mM KH2PO4, 8.6 mM NaCl, 1 mM MgCl2, 0.1 mM CaCl₂, 18 μM FeSO4, 1×MME trace minerals, pH adjusted to 7 with KOH). 1000×MME trace mineral stock solution contains per liter, 1 mL concentrated 1-HCl, 0.5 g Na₄EDTA, 2 g FeCl₃, 0.05 g each H₃BO₃, ZnClz, CuCl₂.2H₂O, MnCl₂.4H₂O, (NH₄)₂MoO₄, CoCl₂.6H₂O, NiCl₂.6H₂O. Unless otherwise noted, all M9* medium was supplemented with 20 mM p-coumarate (neutralized with NaOH) as a sole carbon source.

Production of Base-Catalyzed Depolymerized (BCD) Lignin (BCDL) and Depolymerized Lignin Media Preparation

In brief, dry solid material remaining from the enzymatic hydrolysis of pretreated corn stover (which follows the biorefinery process designed at NREL) was added as 10% (w/v) solids to a 2% NaOH solution and loaded into 200 mL stainless steel reactors. The reaction was carried out at 120° C. for 30 min. The sterile and solubilized material was neutralized with 4N H₂SO₄ and centrifuged at 8,000 rpm for 20 min in aseptic conditions. Then, the supernatant (90% v/v) was mixed with 10×M9* salts (without any nitrogen source) and NH₄Cl to generate M9*-BCDL medium supplemented with either 2 mM or 3 mM NH₄Cl.

Plasmid & Pseudomonas Strain Construction

Phusion® HF Polymerase (Thermo Scientific) and primers synthesized by Eurofins

Genomics were used in all PCR amplifications for plasmid construction. OneTaq® (New England Biolabs—NEB) was used for colony PCR. Plasmids were constructed by Gibson Assembly using NEBuilder® HiFi DNA Assembly Master Mix (NEB) or ligation using T4 DNA ligase (NEB). Plasmids were transformed into either competent NEB 5-alpha F′I^(q) (NEB), Epi400 (Lucigen), or QP15 (Epi400 mated with NEB 5-alpha F′I^(q) to transfer the mini F′ plasmid to Epi400). Standard chemically competent Escherichia coli transformation protocols were used to construct plasmid host strains. Transformants were selected on LB (Miller) agar plates containing 50 pig/mL kanamycin sulfate for selection and incubated at 37° C., Template DNA was either synthesized by IDT or isolated from E. coli or P. putida KT2440 using Zymo Quick gDNA miniprep kit (Zymo Research). Zymoclean Gel DNA recovery kit (Zymo Research) was used for all DNA gel purifications. Plasmid DNA was purified from E. coli using GeneJet plasmid miniprep kit (ThermoScientific) or ZymoPURE plasmid midiprep kit (Zymo Research). Sequences of all plasmids were confirmed using Sanger sequencing performed by Eurofins Genomics. Plasmids used in this work are listed in Table 2.

P. putida JE90, a derivative of P. putida KT2440 where the restriction endonuclease hsdR has been replaced with the Bxb1-phage integrase and respective attB sequence (Elmore, J R., et al., Metabolic Eng. Comm., 5 (2017): 1-8), was used as a parent for all P. putida strains used in this study (Table 1). All genome modifications were performed using either the homologous recombination-based pK18mobsacB kanamycin resistance/sucrose sensitivity selection/counter-selection system (Marx, C J., BMC research notes 1.1 (2008): 1) as described in detail previously (Johnson, C W. et al., Metabolic Eng., 28 (2015): 240-247) or with the Bxb1-phage integrase system (Elmore, J R., et al., Metabolic Eng. Comm., 5 (2017): 1-8) with minor modifications to competent cell preparation procedures. These modifications cultivation overnight to stationary phase, rather than harvesting during exponential growth and all wash steps were performed at room temperature rather than at 4° C. Gene deletions and replacements were performed by homologous recombination, while integration of reporter and itaconate production pathway cassettes was performed with the Bxb1-phage integrase system. Primers used for screening P. putida strains for phaC1ZC2 deletion, ampC::T7_RNAP replacements, and icd/idh start codon swaps can be found below. Integration of pJE990-derivatives using the phage integrase system was confirmed by colony PCR using oligos oJE66 & oJE535.

Plasmid Construction Details

All enzymes used for plasmid construction were purchased from NEB.

For construction of pJE473 (SEQ ID NO: 91), homology arms to target deletion of phaC1ZC2 (PP_5003-5005) were amplified by PCR from wild-type P. putida genomic DNA using primer combinations oJE331/332 and oJE333/334, assembled into gel purified EcoRI/HindIII-linearized pJE382, and transformed into NEB 5-alpha F′I^(Q). Resulting E. coli colonies were screened by colony for the presence of homology arms using primers oJE255/256. Candidates for pJE473 were purified from E. coli and sequenced using primers oJE255/256.

For construction of pJE1031 (SEQ ID) NO: 93), homology arms for the deletion of ampC (PP_2876) were amplified from pJE387 (SEQ ID NO: 90) using primer combination oJE92/608, assembled into gel purified EcoRI/HindIII-linearized pJE382, and transformed into NEB 5-alpha F′I^(Q). Resulting E. coli colonies were screened by colony for the presence of homology arms using primers oJE255/256. Candidates for pJE1031 were purified from E. coli and sequenced using primers oJE255/256.

For construction of pJE1032 (SEQ ID NO: 94), pJE1033 (SEQ ID NO: 95), pJE1037 (SEQ ID NO: 96), and pJE1039 (SEQ ID NO: 97), promoter sequences containing ˜200-300 bp upstream of PP_2685, PP_2688, urtA (PP_4841), and glnK (PP_5234), respectively, were amplified from P. putida and assembled with T7 RNAP and a synthetic terminator sequence. The T7 RNA P polymerase and a downstream terminator was amplified from BL21(DE3) pLysS genomic DNA using oligos oJE625/626. A double terminator sequence for insulation of the construct was amplified from the T7_dbl_term gBlock using oJE627/628. Parts were assembled into BamHI/XbaI-linearized pJE1031, and transformed into NEB 5-alpha F′I^(Q). Resulting E. coli colonies were screened by colony PCR using primers oJE177/178. Candidates for the plasmids were purified from E. coli and sequenced using oJE177/178/631/632/633.

For construction of the reporter plasmids the inventors annealed oligos containing desired promoter sequences and ligated the promoters into a promoterless mNeonGreen reporter plasmid, pJE990 (SEQ ID NO: 92). Plasmid pJE990 was linearized with BbsI. Promoter oligos pairs were phosphorylated with PNK (NEB) in T4 DNA ligase buffer, annealed by heating to 95° C. and cooling at 1° C./minute to room temperature. Annealed oligo sets oJE634/635, oJE97/98/133/134, oJE826/827, oJE828/829, oJE830/831, and oJE832/833 were ligated to BbsI-linearized pJE990 to construct plasmids pJE1040 (SEQ ID NO: 98), pJE1045, pJE1118, pJE1119, pJE1120, and pJE1121 respectively. Ligated DNA was transformed into NEB 5-alpha F′IQ. Plasmids were isolated from transformant colonies and confirmed by sequencing with oJE535. For construction of mKate2 variant plasmids, mKate2 was amplified from the mKate2 gBlock using oligos oJE1724/1725 and digested with NdelI/XbaI. Plasmids pJE1040 and pJE1118-1121 were digested with NdeI/XbaI and ligated with NdeI/XbaI digested mKate2 gBlock to generate plasmids pJE1454-1458. Ligations were transformed into NEB 5-alpha F′IQ, and candidates confirmed by sequencing of isolated plasmid DNA using oligos oJE535/536.

For construction of pJE1180 (SEQ ID NO: 99), the inventors amplified the cat and lysS genes from pLysS as two parts with primers designed to introduce the lysY mutation, assembled the resulting parts into SpeI-linearized pJE1040. Primers oJE817/818 and oJE819/820 were used to amplify the two parts. The resulting lysY/cat fragment was digested with SpeI and ligated into XbaI-linearized pJE1037, generating plasmid pJE1180.

For construction of pJE1380 (SEQ ID NO: 100), codon-optimized cadA from Aspergillus terreus was assembled into NdeI/XbaI-linearized pJE1040—replacing mNeonGreen. The cadA gene was synthesized as gBlocks “cadA_gBlock_1” & “cadA_gBlock_2”, gBlocks 1 & 2 were amplified using oligos oJE1408/1409 and oJE1410/1411, respectively. The assembly was transformed into NEB 5-alpha F′I^(Q), and transformants were screened using oJE535/536. Plasmid DNA was isolated from PCR positive candidates, and sequenced using oJE535/536/1412.

For pJE1390, the cadA gene (encoding the cadA protein shown as SEQ ID NO: 108) from pJE1380 was excised using NdeI/XbaI, and ligated into NdeI/XbaI linearized pJE1045. The ligation was transformed into QP15, and transformants were screened by colony PCR using oligos oJE535/536. The assembly was transformed into NEB 5-alpha F′I^(Q), and transformants were screened using oJE535/536. Plasmid DNA was isolated from PCR positive candidates, and sequenced using oJE535/536/1412.

For pJE1443 (SEQ ID) NO: 101), codon-optimized tad1 and adi1 genes from Ustilago maydis were assembled into AflIII/XbaI-linearized pJE1040—replacing mNeonGreen and its RBS sequence. The tad1 and adi1 (SEQ ID NO: 107) genes were synthesized as gBlocks “tad1” and “adi1”, which were amplified using primer combinations oJE1554/1547 and oJE1555/1548, respectively. The assembly was transformed into NEB 5-alpha F′I^(Q), and transformants were screened using oJE535/536. Plasmid DNA was isolated from PCR positive candidates, and sequenced using oJE535/536/1559/1560/1561.

For pJE1483 (SEQ ID NO: 104), codon-optimized adi1 gene (SEQ ID NO: 107) used for pJE1443 was assembled into AflIII/XbaI-linearized pJE1040—replacing mNeonGreen and its RIBS sequence. The adi1 sequence and its RIBS was amplified from pJE1443 using oligos oJE1760/1761. The assembly was transformed into NEB 5-alpha F′I^(Q), and transformants were screened using oJE535/536. Plasmid DNA was isolated from PCR positive candidates, and sequenced using oJE535/536/1561.

For the construction of the icd/idh start codon swap plasmids pJE1444 (SEQ ID NO: 102) and pJE1445 (SEQ ID NO: 103), several PCR reactions were assembled containing homology arms for targeting, and mutations in the start codons (and RBS neutral mutations in the region between core RBS and start codon) of icd & idh. The homology arms for targeting insertion of the two plasmids into the icd idh locus were amplified using primer pairs oJE1564/1565 and oJE1568/1569 for both plasmids. The central fragment contained between the two homology arms, containing the various mutations, was amplified using oligos oJE1566/1567 for pJE1444 and oligos oJE1570/1571 for pJE1445. The parts were assembled into EcoRI/HindIII-linearized pJE382, transformed into NEB 5-alpha F′I^(Q), and transformants were screened using oJE255/256. Plasmid DNA was isolated from PCR positive candidates, and sequenced using oJE1255/256/1572/1573.

TABLE 3  Oligos used in the disclosure: Oligo Name Oligo Sequence (5′-3′) Purpose oJE255 attaatgcagctggcacgac (SEQ ID NO: 1) primers for screening insertions into the MCS of pJE382 oJE256 agctagatatcgccattcg (SEQ ID NO: 2) primers for screening insertions into the MCS of pJE382 oJE331 tagctcactcaggaaacagctatgacatgattac amplification of homology arms gaattcGACCGAAAACATCGGTGC (SEQ to construction pJE473 for ID NO: 3) deletion of phaC1ZC2 oJE332 tcagcacgtaggtgcctTCTAGAgtctattgtaGG amplification of homology arms ATCCTCTACGACGCTCCGTTG to construction pJE473 for (SEQ ID NO: 4) deletion of phaC1ZC2 oJE333 aCAACGGAGCGTCGTAGAGGATCC amplification of homology arms tacaatagacTCTAGAAGGCACCTACG to construction pJE473 for TGCTG (SEQ ID NO: 5) deletion of phaC1ZC 2 oJE334 ccagtcacgacgttgtaaaacgacggccagtgcca  amplification of homology arms agcttGCAGCCAAAACCGCAG (SEQ ID to construction pJE473 for NO: 6) deletion of phaC1ZC2 oJE335 cagtaccaggcattgctgaa (SEQ ID NO: 7) screening deletion of phaC1ZC2 (flanking) oJE336 gccaaggcagcagctaag (SEQ ID NO: 8) screening deletion of phaC1ZC2 (flanking) oJE337 TGGAGCIGAAGAACGIGTTG (SEQ screening deletion of phaC1ZC2 ID NO: 9) (internal to phaG) oJE338 CTCGTCGACAAACAAAGCAA (SEQ screening deletion of phaC1ZC2 ID NO: 10) (internal to phaG) oJE92 ccagtcacgacgttgtaaaacgacggccagtgcc amplification of ampC deletion aagcttGTAACCACGGCCICACTGAA homology arms for construction (SEQ ID NO: 11) of pJE1031 oJE608 tagctcactcaggaaacagctatgacatgattac amplification of ampC deletion gaattcCTTGCCTCTGCCGGAAAC (SEQ ID homology arms for construction NO: 12) of pJE1031 oJE609  CTGTCGTTTTGTCCGACAATCAAC Amplifies PP_2685 promoter GCGAGCGttaggatccCATCGCCAGTG with overlaps to construct ACAGACTG (SEQ ID NO: 13) pJE1032 oJE610 TGTCAGAGAAGTCGTTCTTAGCGA Amplifies PP_2685 promoter TGTTAATCGTGTTCATGCGGTTTC with overlaps to construct CCTTGTGTIG (SEQ ID NO: 14) pJE1032 oJE611 CTGTCGTTTTGTCCGACAATCAAC Amplifies PP_2688 promoter GCGAGCGttaggatccGCCCGGGTCAA with overlaps to construct AAGCCTTGTCAGAGAAGTCGTTCTT pJE1033 AGCGATGTT (SEQ ID NO: 15) oJE612 AATCGTGTTCATACCCACTCCTTG Amplifies PP_2688 promoter CCGCCGTT (SEQ ID NO: 16) with overlaps to construct pJE1033 oJE619 CTGTCGTTTTGTCCGACAATCAAC Amplifies PP_4841 promoter GCGAGCCTttaggatccATGGCCTCGGG with overlaps to construct GGCTGTTGTCAGAGAAGTCGTTCT pJE1037 TAGCGATGTT (SEQ ID NO: 17) oJE620 AATTCGTGTTCATGTGCTCTCTCCG Amplifies PP_4841 promoter CTGAGT (SEQ ID NO: 18) with overlaps to construct pJE1037 oJE623 CTGTCCITTFIGTCCGACA,ATCAikC Amplifies PP_5234 promoter GCGAGCGttaggatccGCTGCGCACCG with overlaps to construct AAATTG (SEQ ID NO: 19) pJE1039 oJE624 TGTCAGAGAAGTCGTTCTTAGCGA Amplifies PP_5234 promoter TGTTAATCGTGTTCATGAAACTCT with overlaps to construct CTCCCGATTTGG (SEQ ID NO: 20) pJE1039 oJE625 ATGAACACGATTAACATCGCTAA amplification of T7 RNAP for G (SEQ ID NO: 21) construction of pJE1032, 1033, 1037, 1039 oJE626 GTAAAAKFTGCcATccCAACAGC amplification of T7 RNAP for (SEQ ID NO: 22) construction of pJE1032, 1033, 1037, 1039 oJE627 GAGCATCAATATGCAATGCTGTTG amplification of double (SEQ ID NO: 22) terminator from Dbl_term_T7 gBlock for construction of pJE1032, 1033, 1037, 1039 oJE628 CGCTCAACGGACACGCT (SEQ ID amplification of double NO: 24) terminator Dbl_term_T7  gBlock for construction of pJE1.032, 1033, 1037, 1039 oJE629 GACCATTACGGTGAGCGTTT (SEQ Amplifies an internal fragment of ID NO: 25) T7 RNAP for PCR screening oJE630 CGGGTTGAACATTGACACAG (SEQ Amplifies an internal fragment ID NO: 26) of T7 RNAP oJE631 CTCAACAAGCGCGTAGG (SEQ ID Internal sequencing primer for NO: 27) T7 RNAP gene oJE632 GTTCATGCTTGAGCAAGCC (SEQ internal sequencing primer for ID NO: 28) T7 RNAP gene oJE633 GGTGTTACTCGCAGTGTGAC (SEQ Internal sequencing primer for T7 ID NO: 29) RNAP gene oJE634 gtctTAATACGACTCACTATAGGGA Anneal with oJE634 to construct GAGACCTGGAATTGTGAGCGGAT T7 promoter for cloning of AACAATT (SEQ ID NO: 30) pJE1040 oJE635 taagAATTGTTATCCGCTICACAATFC Anneal with oJE635 to construct CAGGTCTCTCCCTATAGTGAGTCG T7 promoter for cloning of TATTA (SEQ ID NO: 31) pJE1040 oJE535 GTTgctagcGTCGGGGTTTGTA (SEQ Screening of genomic integration ID NO: 32) of pJE990/991 and its derivatives into JE90 derivative strains, as well as plasmid sequencing oJE536 aaaaccgcccagtctagctatcg  Screening of genomic (SEQ ID NO: 33) integration of pJE990/991 and its derivatives into JE90 derivative strains, as well as plasmid sequencing oJE93 GGCGTTGCTGGAAGAGTATT (SEQ flanking primers for screening ID NO: 34) ampC deletion oJE94 ACCACTGCCAGCAGAATTG (SEQ flanking primers for screening ID NO: 35) ampC deletion oJE546 gctgttgccatcgatcagt (SEQ ID NO: 36) amplifies internal 851 bp fragment of ampC. Used for screening deletion. oJE547 acgaccagttacaggccaag (SEQ ID NO: 37) amplifies internal 851 bp fragment of ampC. Used for screening deletion. oJE177 GGGAGACGGCTTCATCATG (SEQ Amplifies sequence inserted btw ID NO: 38) homology arms of pJE387/1031 oJE178 ATCACTGTATCCATCTTGTCATG Amplifies sequence inserted btw (SEQ ID NO: 39) homology arms of pJE387/1031 oJE826 gtctTAKIACGACTCACTAtcaaggaaG cloning T7_C4 promoter into ACCTGGAATTGTGAGCGGATAAC pJE990 AATT (SEQ ID NO: 40) oJE827 taagAATTTGTTATCCGCTCACAATTC cloning T7_C4 promoter into CAGGTCttccttgaTAGTGAGTCGTAT pJE990 TA (SEQ ID NO: 41) oJE828 gtoTAATACGACTCACTAcggaagaaG cloning T7_H10 promoter into ACCIGGNATTGTGAGCGGATAAC pJE990 AATT (SEQ ID NO: 42) oJE829 taagAATTGTTATCCGCTCACAATIC cloning T7_H10 promoterinto CAGGTCttcttccgTAGTGAGTCGTAT pJE990 TA (SEQIvD NO: 43) oJE830 gtctTAATACGACTCACTAatactgaaGA cloning T7_H9 promoter into CCTGGAATTGTGAGCGGATAACA pJE990 ATT (SEQ ID NO: 44) oJE831 taagAATTTGTTATCCGCTCACAAVIC cloning T7_H9 promoter into CAGGTCttcagtatTAGTGAGTCGTAT pJE990 TA (SEQ ID NO: 45) oJE832 gtctTAATACGACTCACTAtttcggaaGA cloning T7_G6 promoter into CCTGGAATTGTGAGCGGATAACA pJE990 ATT (SEQ ID NO: 46) oJE833 taagAATTGTTATCCGCTCACAATTC cloning T7_G6 promoter into CAGGTCttccgaaaTAGTGAGTCGTAT pJE990 TA (SEQ ID NO: 47) oJE817 cccgaaaggggggcctatttcgttttggtcca amplify part of pLysS for ctagtCACTATCGACTACGCGATCATG construction of pJE1110 (SEQ ID NO: 48) oJE818 GAAGGCGCTGGTCTTCGCGCCCAT amplify part of pLysS for CATGAGGTGGCGCCGTACGCTTGC construction of pJE1110 CCTTCGTTCGAC (SEQ ID NO: 49) oJE819 TCTCCCACCAACGCTTAAGGTCGA amplify part of pLysS for ACGAAGGGCAAGCGTACGGCGCC construction of pJE1110 ACCTCATGAT (SEQ ID NO: 50) oJE820 CAGGTCTCTCCCTATAGTGAGTCG amplify part of pLysS for TATTAagactactagtCCTGITGATACC construction of pJE1110 GGGAAGC (SEQ ID NO: 51) oJE821 TCACGGACACCAACATTCTGAC sequencing of LysY fragment of (SEQ ID NO: 52) pJE1180 oJE1408 GATAACAATTcttaagattaactcacacagga amplification of cadA gBlocks gatatcat (SEQ ID NO: 53) for pJE1380 construction oJE1409 CCTTTGGTAAACATTTTCAGAAAAC amplification of cadA gBlocks C (SEQ ID NO: 54) for pJE1380 construction oJE1410 GAACGCAGCTATGGGGGTTTTCTG amplification of cadA gBlocks (SEQ ID NO: 55) for pJE1380 construction oJE1411 AAGGCCCCCCGTTAGGGAGGCCT amplification of cadA gBlocks TATTGTTCGTCtctagaTTAGACCAA for pJE1380 construction GG (SEQ ID NO: 56) oJE1412 TGCATAGCGCAAGCATTGTG (SEQ sequencing of cadA in pJE1380 ID NO: 57) oJE1547 ATTCTAGGCACTGCTGTACTGATA amplification of tad1 gBlock for GGGTATTCACGCCGACGATGGAC assembly of pJE1443 (SEQ ID NO: 58) oJE1548 CGTGTGTTGAGCCGTCCATCGTCG amplification of adi1 gBlock for GCGTGAATACCCTATCAGTACAGC assembly of pJE1443 AGTG (SEQ ID NO: 59) oJE1554 TGGAATTGTGAGCGGATAACAAT amplification of tad1 gBlock for TcttaagGTagaTaAGAGCGGGTCATC assembly of pJE1443 G (SEQ ID NO: 60) oJE1555 GTTAGGGAGGCCTTATTGTTCGTCt amplification of adi1 gBlock for ctagaTCAGGACAAGCTCCGGTC assembly of pJE1443 (SEQ ID NO: 61) oJE1559 AGCAACGGITGGATAGCATC (SEQ sequencing of tad1 ID NO: 62) oJE1560 CAGGTCTTTCCCGATGCAAT (SEQ sequencing of tad1 downstream ID NO: 63) genes oJE1561 AACCGCATCCGTCCGATA (SEQ sequencing of adi1 ID NO: 64) oJE1564 cactcaggaaacagctatgacatgattac  amplification of UP homology gaattcgccgccatcaagcagtt  arm for pJE1444/1445 (SEQ ID NO: 65) construction oJE1565 ggataccagaaaatcaaggttccga (SEQ ID amplification of UP homology NO: 66) arm for pJE1444/1445 construction oJE1566 tcggaaccttgattttctggtatccCACC amplification of icd/idh promoter GAAgcactactccgctgtcg  region with GTG start codons for (SEQ ID NO: 67) pJE1444 construction oJE1567 tatagatgatcttggaacgggtgggCACg amplification of icd/idh TTTgttaactactgtgtgctgagc  promoter region with GTG start (SEQ ID NO: 68) codons for pJE1444 construction oJE1568 cccacccgttccaagatcat (SEQ ID NO: 69) amplification of DN homology arm for pJE1444/1445 construction oJE1569 cacgacgttgtaaaacgacggccagtgccaagct amplification of DN homology taacatgatcgggtcgga (SEQ ID NO: 70) arm for pJE1444/1445 construction oJE1570 tcggaaccttgattactggtatccCAACGAAgca amplification of icd/idh promoter ctactccgctgtcg (SEQ ID NO: 71) region with TTG start codons for pJE1445 construction oJE1571 tatagatgatcttggaacgggtgggCAAgTTTgtt amplification of icd/idh promoter aactctctgtgtgagagc (SEQ ID NO: 72) region with TTG start codons for pJE1445  construction oJE1572 cgataccacataatcacgcac (SEQ ID NO: 73) sequencing of pJE1444/1445 oJE1573 ctctcgactttccgctca (SEQ ID NO: 74) sequencing of pJE1444/1445 oJE1574 ttttaggtatccCACCGAA (SEQ ID NO: screening for GTIG start codon 75) swap for icd/idh in P. putida oJE1575 gggtgggCACgTTT (SEQ ID NO:7 6) screening for GTG start codon swap for icd/idh in P. putida oJE1576 gatctggtatccCAACGAA (SEQ ID NO: screening for TTG start codon 77) swap for icd/idh in P. putida oJE1577 cgggtgggCAAgTTT (SEQ ID NO: 78) screening for TTG start codon for icd/idh in P. putida oJE1578 gattttctggtatcccatgct  screening for wild-type start (SEQ ID NO: 79) codon oJE1579 gtgggcatgcgg (SEQ ID NO: 80) screening for wild-type start codon oJE1580 gtggcgatcacgtcgtact (SEQ ID NO: 81) screening to ensure that plasmid backbone is removed following start codon swap oJE1581 aggaggtgatgcctttgtc (SEQ ID NO: 82) screening to ensure that plasmid backbone is removed following start codon swap oJE1582 aggaatgatcggaggtcag (SEQ ID NO: 83) sequencing of icd promoter region. Use with oJE1581 to amplify region for sequencing. oJE66 catgtagttgtaggcgtcttc  screening integration of pJE990- (SEQ ID NO: 84) derivative plasmids via the Bbx1- phage integrase system

Growth Rate Analysis

LB medium was inoculated from glycerol stocks and incubated overnight at 30° C., 250 rpm for precultures. Cultures were washed twice by centrifugation (˜4000×g for 10 minutes) and resuspension in equal volumes of 1×M9 salts lacking NH₄Cl to remove residual LB medium, and resuspended in ⅓ volume 1×M9 salts. Optical density (OD600) of resulting suspensions was measured using a 1 cm path length cuvette. Growth assays were performed with 600 μL M9* medium supplemented with 20 mM p-coumarate and 20 mM NH₄Cl in clear 48-well microtiter plates with an optically clear lid (Greiner Bio-One). All cultures were inoculated with washed cultures to an OD₆₀₀ equivalent to 0.03 in a 1 cm pathlength cuvette. Plates were incubated at 30° C., fast shaking in an Epoch2 plate reader (Bio-Tek), with OD₆₀₀ readings taken every 10 minutes. Exponential growth rates were determined using the CurveFitter software with data points in early mid-log phase. All growth rates were calculated from 3 replicate experiments.

Fluorescent Reporter Assays

Strains were revived from glycerol stocks in 5 mL LB with overnight incubation at 30° C., 250 rpm. 5 mL starter cultures in M9*+20 mM glucose+10 mM NH₄Cl were inoculated with 1% of the recovery culture and similarly incubated. Coupled growth and fluorescence assays were performed with a Neo2SM (Bio-Tek) plate reader using 200 μL/well of M9*+20 mM p-coumarate+2 (limiting) or 20 (replete) NH₄Cl in black-walled, μClear® flat-bottom, 96-well plates (Greiner Bio-One) with an optically clear lid. Plate cultures were inoculated with 0.5% inoculum from starter cultures, and incubated overnight at 30° C., fast shaking with OD₆₀₀ and fluorescence (F_(510,530) for mNeonGreen and F_(588,633) for mKate2) measured every 10 minutes. Reporter expression per cell was estimated by dividing relative fluorescence units (RFU) by OD₆₀₀ (as a proxy for cell number) for each time point and averaging those values for time points occurring during either exponential growth or stationary phase. Background absorbance and fluorescence readings from wells containing media blanks were averaged and subtracted from sample readings prior to analysis. Exponential phase was defined as time points where OD₆₀₀ was between 0.039 and the OD₆₀₀ curve inflection point, typically OD₆₀₀˜0.2 (nitrogen limited) or ˜0.6 (nitrogen replete). Stationary phase was defined as time points starting 2 hours following end of exponential phase.

Shake Flask Experiments

Starter cultures were prepared as described for growth rate assays with the exception that 50 μg/mL kanamycin sulfate was added to the medium. Starter cultures were inoculated to a final OD₆₀₀ of 0.1 into 25 mL of M9* medium, supplemented with 20 mM p-coumarate and 2 mM NH₄Cl, in a 125 mL erlenmeyer flask and incubated at 30° C., 250 rpm. Cultures were sampled periodically to measure growth by OD₆₀₀, and analyte concentrations by high performance liquid chromatography (HPLC).

Analytical Techniques

For shake flask experiments, optical density at 600 nm (OD₆₀₀) was measured using a spectrophotometer (Amersham, UltroSpec10). HPLC analysis for p-coumarate and organic acid detection was performed by injecting 20 μL of 0.2 μm filtered culture supernatant onto a Waters 1515 series system equipped with a Rezex RFQ-Fast Acid H+ (8%) column (Phenomenex) and a Micro-Guard Cation H⁺ cartridge (Bio-Rad). Samples were run with column at 60° C. using a mobile phase of 0.01 N sulfuric acid at a flow rate of 0.6 mL/min, with a refractive index detector and UV/Vis detector measuring A230 & A280 for analyte detection. Analytes were identified and quantified by comparing retention times and spectra with pure standards.

For shake flask experiments with M9*-BCDL, optical density at 600 nm (OD₆₀₀) was measured with a Nanodrop (ThermoFisher Scientific) after diluting samples 6-fold. Uninoculated M9*-BCDL medium was used as a blank to subtract signal coming from components in the medium.

Itaconic acid quantitation in M9*-BCDL. Prior the analysis, a 0.1 mL. aliquot was taken from each sample and 0.9 mL of water were added to make a 10× dilution. Then, 34 μL of 72% sulfuric acid were added to each diluted sample to decrease the pH below 2.0 and precipitate acid insoluble lignin. Samples were centrifuged, and the supernatant was filtered through a 0.2 μM filter pore size. Itaconic acid quantification was performed on an Agilent 1100 series HPLC system, with a diode array detector (DAD) at 210 nm (Agilent Technologies). Analysis was performed by injecting 6 μL of filtered culture supernatant onto a Phenomenex Rezex™ RFQ-Fast Acid H+ (8%) column with a cation H+guard cartridge (Bio-Rad Laboratories) at 85° C. using a mobile phase of 5 mM sulfuric acid at a flow rate of 1.0 mL/min.

Aromatic compounds quantitation in M9*-BCDL. Metabolite analysis in BCD was performed on an Agilent 1200 LC system (Agilent Technologies) equipped with a DAD. Each sample and standard was injected at a volume of 10 μL onto a Phenomenex Luna C18(2) column 5 μm, 4.6×150 mm column (Phenomenex). The column temperature was maintained at 30° C. and the buffers used to separate the analytes of interest were A) 0.05% acetic acid in water and B) 0.05% acetic acid in acetonitrile. The chromatographic separation was carried out using a gradient of: initially starting at 1% B going to 50% B at 35 min before immediately switching to 99% B at 35.1 min, before equilibrium for a total run time of 47 min. The flow rate of the mobile phases was held constant at 0.6 mL/min. The same standards used in the BCDL experiments were also used to construct calibration curves, but between the ranges of 5-200 μg/L. Three separate wavelengths from the DAD were used to identify and quantitate the analytes of interest. A wavelength of 210 nm and 225 nm was used for the analytes vanillic acid and 4-hydroxybenzoic acid. A wavelength of 325 nm was used for the analytes p-coumaric acid, and ferulic acid. A minimum of five calibration levels was used with an r² coefficient of 0.995 or better for each analyte.

Transcriptional Profiling of P. putida

For the determination of NO₃ induced promoters, strain JE1657, an engineered P. putida strain containing a Bxb1 phage integrases system for rapid genomic integration of DNA 3, and a PT7:mNeonGreen reporter cassette was used. JE1657 was cultured at 30 C in 50 mL MME mineral medium in a 250 mL erlenmeyer shake flask at 30° C., 250 rpm shaking and harvested mid-log (OD600=˜0.2) by centrifugation (˜16,000×g, 2 minutes, 4° C.). Supernatants were quickly decanted, and cell pellets were frozen rapidly in liquid nitrogen prior to storage at −80° C. for storage prior to RNA isolation. Four samples were prepared for each condition for characterization of biosensor performance strain JE2212 under identical conditions.

Cell pellets were resuspended in TRIzol (ThermoFisher-Invitrogen, Waltham, Mass. USA) and processed according to the manufactures protocol for TRIzol reagent. In general, TRIzol was added to cell pellets and mixed by vortex and pipetting. Chloroform was then added and mixed and samples were centrifuged. After centrifugation the aqueous layer was removed and mixed 1:1 with 80% ethanol. The samples were then purified on a RNeasy column (Qiagen Hilden, Germany) following the manufactures protocol and the on-column DNase digestion. RNA was eluted off the column in 35 μL RNAse free H20 (Qiagen, Hilden, Germany). RNA concentration was quantified using a Nanodrop 1000 instrument (ThermoScientific, Waltham, Mass.) and RNA quality was verified by obtaining RNA Integrity Numbers (RIN) using an RNA 6000 Nanochip on an Agilent 2100 Bioanalyzer (Agilent Technologies, Santa. Clara, Calif.).

Ribosomal RNA was depleted from total RNA samples using a RiboZero rRNA Removal Kit (Epicentre-Illumina Inc. San Diego, Calif.) according to manufacturer's instructions. The depleted sample was purified on a RNA Clean & Concentrator-5 (Zymo Research, Irvine, Calif., USA) following the manufacturer's protocol, and then the depleted material was quantified using a Nanodrop 1000 and visualized on an Agilent 2100 Bioanalyzer instrument with a RNA 6000 Nanochip (Agilent Technologies, Santa Clara, Calif.). RNA depleted of ribosomal RNA was used as input material to synthesize cDNA libraries using a ScriptSeq v2 RNA-Seq Library Preparation Kit (Illumina-Epicentre, San Diego, Calif., USA) according to manufacturer's instructions and TruSeq compatible barcodes. Pooled barcoded libraries were sequenced in one direction for 50 bases (SE50) on an Illumina Hi-Seq2500 using v4 chemistry (Illumina Inc. San Diego, Calif.) and de-multiplexed as a sequencing service provided by The Genomic Services Lab at Hudson Alpha Institute for Biotechnology (HudsonAlpha, Huntsville, Ala.).

Differential Gene Expression Analysis

After Illumina sequencing, RNA-seq reads were mapped to modified versions of the P. putida KT2440 reference genome (NC_002947) containing the mutations found in JE1657 and JE2212 using the Geneious for RNA-seq mapping workflow. Read count per annotated gene was calculated for each treatment and replicate, as well as fragment per kilobase million (FPKM), a common normalization technique. The inventors then exported gene locus tags and raw read counts into tab-delimited files, one for each replicate. To calculate differential gene expression, R package DESeq was used which calculates log-fold change in expression and allows comparison between treatments using several replicates. There were three (JE2212 assay) or four (JE1657 assay) replicates per treatment, for a total of six or eight inputs per experiment.

Gene and Protein Sequences

SEQ ID) NO: 105: cadA gene (Codon-optimized for P. putida KT2440).

SEQ ID NO: 106: tad1 gene (Codon-optimized for P. putida KT2440).

SEQ ID NO: 107: adi1 gene (Codon-optimized for P. putida KT2440).

SEQ ID NO: 108: cadA protein (Organism: Aspergillus terreus).

SEQ ID NO: 109: tad1 protein (Organism: Ustilago maydis).

SEQ ID NO: 110: adi1 protein (Organism: Ustilago maydis).

SEQ ID NO: 111: itp1 (itaconate transporter) protein (Organism: Ustilago maydis)

SEQ ID NO: 112: TbrB (trans-aconitate transporter) protein (Organism: Bacillus thuringiensus CT-43)

Example 2: Dynamic Regulation Enables Two-Stage Production of Itaconate Production from Lignin-Derive Aromatics

The enzyme cis-aconitate decarboxylase produces itaconic acid (itaconate) by enzymatic decarboxylation of the TCA cycle intermediate cis-aconitate (FIG. 1B). In the fungus Aspergillus terreus, the cadA gene encodes cis-aconitate decarboxylase, and is the sole enzyme required for production of itaconate from the TCA cycle intermediate cis-aconitate. In P. putida, many aromatic compounds derived from lignin are funneled from numerous peripheral catabolic pathways into the intermediates catechol or protocatechuate, which are further metabolized by the β-ketoadipate pathway to produce an acetyl-CoA and succinate (FIG. 1A). The production of a single itaconate requires condensation of an acetyl-CoA and oxaloacetate, which is readily produced from succinate, into a citrate molecule, which can then be dehydrated to the immediate precursor cis-aconitate (FIG. 1B).

The inventors constructed an expression cassette containing codon optimized version of the ca A gene (SEQ ID NO: 105) under the control of the T7 promoter in a Bxb1 integrase target plasmid for rapid integration into the P. putida genome. This plasmid was integrated into the genome of P. putida JE2113 (Table 1), a host strain containing the P_(urtA):T7 RNAP:lysY+ cassette, generating strain JE3128. Itaconic acid production by JE3128 was assayed by shake flask cultivation with M9* medium supplemented with 20 mM p-coumarate, a model lignin-derived aromatic compound, and limiting amounts of nitrogen (2 mM N₄Cl). With this strain and conditions, the inventors were able to detect production of itaconic acid, but the titer (23 mg/L) and molar yield (0.96% mol/mol) were low (Table 4).

TABLE 4 Production of itaconate from lignin-derived aromatics. Stationary Overall Phase Hosted Molar Molar Mass Production Yield Yield* Yield Titer Strain Pathway Relevant genotype (mol/mol) (mol/mol) (g/g) (g/L) JE3128 PT7:cad4 JE90P_(urtA):T7_RNAP:Pcat:lysY 0.01 n.d. 0.01 0.02 (cis) JE3221 PT7:cadA JE90P_(urtA):T7_RNAP:Pcat:lysY 0.09 0.18 0.07 0.22 (cis) ΔphaC1ZC2 JE3659 PT7:tad1:adi1 JE90 0.23 0.39 0.19 0.57 (trans) P_(urtA):T7_RNAP:Pcat:lysY ΔphaC1ZC2 JE3713 PT7:cadA JE90 0.29 0.79 0.23 0.72 (cis) P_(urtA):T7_RNAP:Pcat:lysY ΔphaC1ZC2 icdGTG:idhGTG JE3715 PT7:tad1:adi1 JE90 0.43 1.02 0.34 1.09 (trans) P_(urtA):T7_RNAP:Pcat:lysY ΔphaC1ZC2 icdGTG:idhGTG JE3717 PT7:cadA JE90 0.50 0.97 0.40 1.27 (cis) P_(urtA):T7_RNAP:Pcat:lysY ΔphaC1ZC2 icdTTG:idhTTG JE3719 PT7:tad1:adi1 JE90 0.56 1.16 0.45 1.26 (trans) P_(urtA):T7_RNAP:Pcat:lysY ΔphaC1ZC2 icdTTG:idhTTG

P. putida is well known to accumulate polyhydroxyalkanoates (PHA), a fatty acid-derived carbon storage polymer, from a variety of carbon sources, including lignin (Linger, J G., et al., PNAS 111.33 (2014): 12013-12018), in conditions where nitrogen is limited (Prieto, A. et al., Environmental Microbiology, 18.2 (2016): 341-357). Depending on the conditions, PHAs can accumulate to up to 8004 cell dry weight. As production of PHAs requires acetyl-CoA for production of fatty acid intermediates, it directly competes with itaconate production for acetyl-CoA (FIG. 1A). The inventors hypothesized that preventing the cell from producing PHAs, by deletion of the PHA synthetase genes, phaC1 and phaC2, would increase the flux of carbon during nitrogen-starvation towards the TCA cycle and itaconate production. The phaC1ZC2 operon was deleted from JE2113—generating strain JE3215, integrated the PT7:cadA cassette into JE3215 to generate strain JE3221, and tested this strain for production of itaconate from 20 mM p-coumarate under nitrogen-limited conditions. As predicted, removal of the competing pathway significantly increased titer (220 mg/L) and overall molar yield (8.56% mol/mol) (Table 4, FIG. 2A). In the first 24 hours, all of the growth occurs and some itaconate is formed—likely after the initial growth period—with a molar yield of 5.49%. However, the itaconate yield in the subsequent production/stationary phase was substantially higher (17.8% mol/mol) and accounted for over half of the total itaconate production.

Example 3: Metabolic Pathway Selection to Optimize Itaconate Production

To date, other than in organisms that natively produce itaconate, all attempts to engineer strains for itaconate production have focused on heterologous expression the cis-aconitate decarboxylase, or cis-pathway, from A. terreus. However, an alternate pathway for itaconate production was recently discovered in Ustilago maydis (Geiser et al., Microbial Biotech., 9.1 (2016): 116-126). This pathway, referred to here as the trans-pathway, proceeds through two steps. First, cis-aconitate is isomerized to the thermodynamically favorable isomer, trans-aconitate, by aconitate isomerase (adi1, P. putida KT2440 protein sequence SEQ ID NO: 110), which is subsequently decarboxylated by trans-aconitate decarboxylase (tad1, P. putida KT2440 protein sequence SEQ ID NO: 109) generating itaconate (FIG. 1B). At equilibrium, the trans isomer comprises 88% of aconitate. Furthermore, trans-aconitate is not a substrate of aconitate hydratase, and also inhibits the aconitase enzyme. Taken together, the inventors hypothesized that the trans-pathway would improve itaconate production relative to the cis-pathway by providing a thermodynamically favorable route to divert carbon flux from the TCA cycle.

To test this hypothesis, the inventors constructed an expression cassette with the T7 promoter controlling expression of codon-optimized version of the tad1 & adi1 genes. The resulting plasmid was integrated into the genome of JE3215, generating strain JE3659. JE3659 was assayed for production of itaconate from p-coumarate under nitrogen-limited conditions. As hypothesized, utilization of the trans-pathway from U. maydis further increased both the titer (570 mg/L) and molar yield (23.39% mol/mol) (Table 4, FIG. 2B). Supporting the notion that diverting carbon out of the TCA cycle may improve yields, the inventors observed transient accumulation of up to 0.6 mM of the intermediate trans-aconitate. As observed with JE3221, itaconate yield in the stationary phase was substantially higher (38.79% mol/mol) than in the first 24 hours (16.84% mol/mol).

Example 4: Modulating TCA Cycle Flux Increases Itaconic Acid Yields and Titer

One of the most reliable methods to increase product formation in a chemical reaction is to increase substrate concentration. As an obligate aerobe, P. putida maintains robust TCA cycle activity for energy production. The inventors hypothesized that the increased substrate accumulation with the trans pathway was the determining factor for the increase itaconate yields of JE3659 (trans) relative to JE3221 (cis). Accordingly, it was predicted that increasing accumulation of cis-aconitate would significantly increase yields. Reducing the flux through isocitrate dehydrogenase (FIG. 1B—icd idh), which decarboxylates isocitrate in a reaction that is essentially irreversible, should increase accumulation of the itaconate precursor cis-aconitate. Deletion of the two isocitrate dehydrogenase genes (icd & idh) in P. putida would likely produce a severely energy-starved, α-ketoglutarate auxotroph during growth on lignin-derived aromatics, so the inventors aimed to decrease expression of these enzymes instead. To reduce translational efficiency of the icd & idh genes, the start codons of each isocitrate dehydrogenase in JE3215 was altered from ATG to either GTG or TTG generating strains JE13674 and JE3681, respectively.

As these mutations are predicted to increase substrate accumulation for both the trans- and cis-pathways, itaconate production was tested with both pathways in JE3674 and JE3681 host strains. The cis- and trans-pathways were integrated into JE3674, generating strains JE3713 (cis) and JE3715 (trans), and JE3681, generating strains JE3717 (cis) and JE3719 (trans). All 4 strains were assayed for production of itaconate from p-coumarate under nitrogen-limited conditions. As hypothesized, the mild reduction of isocitrate dehydrogenase activity induced by the GIG start codons significantly increased itaconate titers and overall yields (FIGS. 3A-3B, Table 4) in both JE3713 (720 mg/L, 28.64% mol/mol) and JE3715 (1.09 g/L, 43.27% mol/mol). The additional reduction of isocitrate dehydrogenase activity with the TTG start codons even further increased overall itaconate production (FIGS. 3C-3D, Table 4). When compared to JE3717 (1.27 g/L, 50.37% mol/mol), containing the cis-pathway, the shift from GTG to TTG start codons in the trans-pathway strain JE3719 had less impact on itaconate yields (1.26 g/L, 56.52% mol/mol). As observed previously, the yield of itaconate from p-coumarate is substantially higher in stationary phase than the overall yields, and for all strains except JE3713 the molar yield is near or above 100% (Table 4).

Example 5: Production of Trans-Aconitate from Lignin-Derived Aromatics

Trans-aconitate, an intermediate in the production of itaconate with the trans-pathway, is a compound with potential industrial value as well. If production of trans-aconitate becomes commercially viable, there are uses for trans-aconitate in the production of materials such as plasticizers and building blocks for hyperbranched polyesters, among others. Given the robust itaconate production by the instant engineered P. putida strains, the inventors hypothesized that they might also be able to produce high yields of trans-aconitate from lignin-derived aromatics using a truncated version of the trans-pathway. To test this hypothesis, the inventors constructed an expression cassette with a truncated version of the itaconic acid production trans-pathway that lack the trans-aconitate decarboxylase gene tad1, and contains just the aconitate isomerase, adi1, under the control of the T7 promoter. This cassette was incorporated into strain JE3681, generating strain JE3899. JE3899 was tested for production of trans-aconitate form p-coumarate under nitrogen-limited conditions. After 72 hours most of the p-coumarate was consumed and 1.51 g/L trans-aconitate was produced (FIG. 4). The yield was high with molar and mass yields of 53.17% mol/mol and 56.43% g/g, respectively.

Example 6: Modulating TCA Cycle Flux Increases Itaconic Acid Yields and Titer

As an obligate aerobe, P. putida maintains robust TCA cycle activity for energy production. The inventors hypothesized that reducing flux through isocitrate dehydrogenase (FIG. 1B—icd, idh), should increase accumulation of cis-aconitate, and therefore increase yields. Deletion of icd and idh would make P. putida an energy-starved, α-ketoglutarate auxotroph, and likely be unable to grow on lignin-derived substrates. Instead, the inventors aimed to reduce translation efficiency of icd & idh by altering the start codons to GTG or TTG, generating strains JE4296 and JE4273, respectively, Cell yield (as measured by OD₆₀₀) was largely unaffected by the start codon alterations. The growth rate of JE4296 was also unaffected, while the growth rate of JE4273 on p-coumarate was decreased by 43.5% (FIG. 1E).

To determine the impact of these mutations on itaconate production, the inventors integrated the Ptac:cadA cassette into both strains, generating strains JE4308 (icdGTG:idhGTG) and JE4307 (icdTTG:idhTITG), and assayed itaconate production from p-coumarate under nitrogen-limited and nitrogen-replete conditions. Slowing the TCA cycle was sufficient to allow detectable itaconate production under nitrogen-replete conditions, and further increased yields under nitrogen-limited conditions to 26.5% and 30.47% mol/mol with JE3708 and JE3707, respectively (FIG. 1D), While yields improved, the detrimental effect of constitutive cadA expression was highlighted by decreased growth rates in strains expressing cadA (FIG. 1E). Growth rates in all three genetic backgrounds were negatively impacted by constitutive cadA expression, with impact being most pronounced in the JE4273 (icd^(TG):idh^(TTG)) background where it caused a 36.5% reduction in growth rate.

Example 7: Development of a Signal-Amplified Nitrogen-Limitation Biosensor for Dynamic Metabolic Control in Pseudomonas putida KT2440

By limiting its expression to production phase, dynamic regulation of the apparently toxic CadA protein could substantially improve itaconate production. Native regulatory systems are specifically tuned to provide expression sufficient for associated pathways which is often insufficient for heterologous pathways. Utilizing an orthogonal RNA polymerase intermediary, such as T7pol for dynamic regulation allows amplification of the original signal (FIG. 7A).

Here the inventors develop a biosensor that limits protein expression to production phase by controlling expression of T7pol with a nitrogen-sensitive promoter. Eleven candidate promoters were identified by comparing gene expression during growth on a good (NI-L) or poor (NO₃) nitrogen source (Table 5).

Table 5: Differential expression of genes downstream potential nitrogen-sensitive promoters.

log₂ fold change Locus Gene (NaNO₃/ Base Tag Name NH₄Cl) Mean Predicted gene function PP_1705 nirB 8.14 2029.14 nitrite reductase large subunit PP_2092 nasA 6.31 361.67 nitrate transporter PP_2094 nasS 2.79 51.23 nitrate binding protein PP_2685 — 4.44 320.51 Bacterial proteasome, beta subunit PP_2688 — 3.99 132.41 Circularly permuted ATP- grasp type 2 PP_2842 ureD 4.38 181.83 urease accessory protein PP_4053 treY 2.19 1151.28 maltooligosyl trehalose synthase PP_4841 urtA 4.37 455.68 urea ABC transporter substrate-binding protein PP_4842 urtB 4.56 72.42 urea ABC transporter permease PP_4845 urtE 3.77 67.21 ABC transporter ATP- binding protein PP_5234 glnK 1.45 8496.51 NRII(GlnL/NtrB) phosphatase activator

The inventors tested biosensors with four candidate promoters: P_(PP_2685), P_(PP_2688), P_(urtA), and P_(glnK). Candidate biosensors were integrated into the JE90 genome, replacing a β-lactam resistance gene, ampC, and assayed for production of the fluorescent protein mNeonGreen under either nitrogen-replete or nitrogen-limited conditions (FIGS. 7B-7D). While the P_(glnK) and P_(PP_2685) candidate biosensors were surprisingly nitrogen-agnostic, displaying constitutive mNeonGreen expression similar to the σ⁷⁰ tac promoter (FIGS. 6A-6B), the other candidate P_(PP_2688)- and P_(urtA)-based biosensors responded to nitrogen-limitation, demonstrating 3.7 and 8.8-fold mNeonGreen induction upon entry into nitrogen-depletion-induced stationary phase (FIG. 7D).

While the initial P_(urtA) biosensor variant allowed strong induced expression, basal expression in the presence of nitrogen was relatively high. To reduce basal T7pol activity the inventors constitutively expressed a catalytically-deactivated variant of T7 lysozyme (LysY) (U.S. Pat. No. 8,138,324), which allosterically inhibits T7pol activity (FIG. 7A). The expression of LysY substantially improved biosensor performance: decreasing basal mNeonGreen expression by 78% in exponential phase, and increasing the maximal induced mNeonGreen expression level, resulting in 60-fold mNeonGreen induction, a 6.8-fold improvement (FIG. 7D). As an orthogonal measurement of biosensor performance, the inventors utilized RNAseq to compare gene expression with NH₄ and NO₃ as described previously. Highlighting the function of this biosensor as a signal amplifier, NO₃-induced mNeonGreen mRNA abundance was 302- and 54-fold higher than urtA and T7pol.

Optimal pathway performance often requires tuning expression of individual proteins. Tuning expression can be achieved with promoter (Elmore et al., Metab Eng Commun 5, 1-8 (2017)) and/or ribosome binding site (RBS) (Salis et al., Nature Biotech. 27.10 (2009): 946) modifications. The inventors utilized a small library of T7 promoter variants (see Table 6) with the red fluorescent protein mKate2 to demonstrate ability to tune the magnitude of biosensor outputs. Unlike the σ⁷⁰ tac promoter (FIG. 6A) which was constitutively expressed, nitrogen-limitation was required for induction of mKate2 production in all five T7 promoter variants (FIG. 7E, Table 6). With the promoter library we could tune maximal protein expression over an 89-fold range. Interestingly, the inventors observed a 2-3.5 fold dynamic range improvement over the T7 promoter with three of the variant promoters—largely driven by considerably lower basal expression—which approached the background autofluorescence.

TABLE 6  T7 Promoter variant testing. mKate2 production Fold-induction T7 Promoter (RFU/OD600) in Variant  Nitrogen-limited N-limited Promoter Sequence Exponential Stationary stationary phase Ptac — 43755 ± 1546  54287 ± 572   1.24 ± 0.03 (const.) PT7  taatacgactca 979 ± 30  73036 ± 2563  74.67 ± 4.76 ctaTAGGGgaa (SEQ ID  NO: 85) PT7_C4  taatacgactca 95 ± 24 12847 ± 416   142.61 ± 36.75  ctaTTCAAGgaa (SEQ ID  NO: 86) PT7_H10 taatacgactca 79 ± 28 17782 ± 301   262.27 ± 1977   ctaCGGAAgaa (SEQ ID  NO: 87) PT7_H9 taatacgactca 91 ± 9  14110 ± 126   157.16 ± 17     ctaATACTgaa (SEQ ID  NO: 88) PT7_G6 taatacgactca 74 ± 38 817 ± 12  15.92 ± 12.22 ctaTTTCCTgaa (SEQ ID  NO: 89)

Example 8: Dynamic Regulation Improves Two-Stage Production of Itaconate Production from Lignin-Derived Aromatics

The inventors next sought to test whether dynamic regulation of cadA would improve itaconate production. For this, the inventors altered the isocitrate dehydrogenase start codons of JE2113, which contains P_(urtA):T7pol:lysY⁺ biosensor cassette, to generate strains JE3674 (icd^(GTG):idh^(GTG)) and JE3681 (icd^(TTG):idh^(TTG)). The inventors integrated a codon optimized copy of cadA (SEQ ID NO: 105) under the control of the T7 promoter into all three strains, and assayed production of itaconate from p-coumarate under nitrogen-limited conditions, Similar to previous shake flask experiments—with the exception of JE4307—growth is complete with the first 24 hours, with some itaconate production occurring, likely after growth is completed. Strain JE3717 (P_(T7):cadA, icd^(TTG):idh^(TTG)) achieved an itaconate yield of 510% mol/mol (FIG. 8A, Table 1), a 67% improvement over the best performing constitutive cadA expression strain, JE4307 (P_(tac):cadA, icd^(TTG):idh^(TTG)) (FIG. 1D). Itaconate yields with JE3221 (icd^(ATG):idh^(ATG)) and JE3713 (icd^(GTG):idh^(GTG)) were similar to those of their corresponding constitutive cadA strains (FIG. 1D, FIG. 8D), with slightly higher molar yield for JE3713 over JE4308 (29.1% vs. 26.5%). Furthermore, dynamic regulation of ca LA eliminated the growth defect induced by cadA expression (FIG. 8B), which has ramifications on itaconate productivity—at 48 hours JE3717 itaconate production is essentially complete (FIG. 8A), while production by JE4307 was not complete after 72 hours (FIG. 1D). Taken together, dynamic regulation of cadA has demonstrable improved performance, and will likely improve strain stability.

Example 9: Metabolic Pathway Selection to Optimize Itaconate Production

To date, other than in organisms that natively produce itaconate, attempts to engineer strains for itaconate production have focused on heterologous expression the cis-aconitate decarboxylase (termed here the cis-pathway) from A. terreus. However, an alternate pathway for itaconate production was recently discovered in Ustilago maydis (Geiser et al., Microbial Biotech., 9.1 (2016): 116-126). This pathway, referred to here as the trans-pathway, proceeds through two steps. First, cis-aconitate is isomerized to the thermodynamically favorable isomer, trans-aconitate, by aconitate isomerase (adi1), which is subsequently decarboxylated by trans-aconitate decarboxylase (tad1) generating itaconate (FIG. 1B). The trains isomer comprises 88% of aconitate at equilibrium and is a competitive inhibitor of aconitase enzyme (Gawron et al., Biochimnica et Biophysica Acta (BBA)-Enzymology, 484.2 (1977): 453-464)—both features that could increase substrate accumulation.

Taken together, the inventors hypothesized that the trans-pathway would improve itaconate production relative to the cis-pathway by providing a thermodynamically favorable route to divert carbon flux from the TCA cycle. To test this hypothesis, the inventors integrated codon-optimized tad1 (SEQ) ID NO: 106) and adi1 (SEQ ID NO: 105) genes under the control of the T7 promoter into strains JE3674 and JE3681 and assayed the resulting strains JE3715 and JE3719, respectively, for itaconate production (FIG. 8C). As hypothesized, strains expressing the trans-pathway from U. maydis produced higher molar yields than equivalent strains expressing the cis-pathway (FIG. 8D, Table 7), and JE3719 produced the highest itaconate yield (56.4%) from p-coumarate in this study.

TABLE 7 Production of itaconic acid from p-coumaric acid Stationary Overall Phase Hosted Molar Molar Mass Production Relevant Parent Yield Yield* Yield Titer Strain Pathway Genotype (mol/mol) (mol/mol) (g/g) (g/L) JE4305 P_(tac):cadA JE90(Pseudomonas putida 0.04 0.1 0.03 0.02 (cis) KT2440 ΔhsdR::Bxb1int- attB) JE4306 P_(tac):cadA JE90 ΔphaC₁ZC₂ 0.12 0.33 0.09 0.12 (cis) JE4308 P_(tac):cadA JE90 ΔphaC₁ZC₂ 0.27 0.72 0.21 0.34 (cis) icd^(GTG):idh^(GTG) JE4307 P_(tac):cadA JE90 ΔphaC₁ZC₂ 0.3 n.d.** 0.24 0.75 (cis) icd^(TTG):idh^(TTG) JE3221 P_(T7):cadA JE90 0.09 0.18 0.07 0.22 (cis) P_(urtA):T7pol:P_(cat):lysY ΔphaC₁ZC₂ JE3713 P_(T7):cadA JE90 0.29 0.79 0.23 0.81 (cis) P_(urtA):T7pol:P_(cat):lysY ΔphaC₁ZC₂ icd^(GTG):idh^(GTG) JE3715 P_(T7):tad1:adi1 JE90 0.43 1.02 0.34 1.09 (trans) P_(urtA):T7pol:P_(cat):lysY ΔphaC₁ZC₂ icd^(GTG):idh^(GTG) JE3717 P_(T7):cadA JE90 0.5 0.97 0.4 1.27 (cis) P_(urtA):T7pol:P_(cat):lysY ΔphaC₁ZC₂ icd^(TTG):idh^(TTG) JE3719 P_(T7):tad1:adi1 JE90 0.56 1.16 0.45 1.26 (trans) P_(urtA):T7pol:P_(cat):lysY ΔphaC₁ZC₂ icd^(TTG):idh^(TTG) *Stationary phase molar yield was calculated using itaconate yield from 24 to 96 hour time points. **Not Determined.

Example 10: Production of Itaconate from Depolymerized Lignin

To test the viability of itaconate production from lignin, we assayed the ability of strain JE3715 to upgrade a depolymerized lignin stream produced from an industrially-relevant lignocellulose deconstruction process (Rodriguez, Acs Sustain Chem Eng 5, 8171-8180 (2017)) to itaconate. Base-catalyzed depolymerization of washed lignin was performed as described previously (Rodriguez, Acs Sustain Chem Eng 5, 8171-8180 (2017)), and the resulting liquor (BCDL) was diluted with concentrated modified M9 salts containing either 2 or 3 mM NH₄Cl. This medium was analyzed and found to contain ˜1.74 g/L p-coumarate, 0.5 g/L ferulic acid (ferulate), trace amounts of other monomeric carbon sources, and residual higher molecular weight lignin. JE3715, chosen as a compromise between itaconate yield from coumarate and productivity, was inoculated into shake flasks containing the two media variants and assayed for itaconate production. Production of itaconic acid leveled off at 48 hours with titers between 1.4 and 1.43 g/L (FIG. 8E). The high apparent yields (98.8% molar yield and 0.79 g itaconate/g aromatic monomer) suggest that not only is depolymerized lignin a great substrate for itaconate production, but that the performance JE3715 is enhanced by components of the lignin and/or may also be consuming additional higher molecular weight lignin.

Example 11: Production of Itaconic Acid and Trans-Aconitate from Diverse Substrates

Tables 8 and 9 summarize embodiments where itaconic acid (Table 8) and trans-aconitate (Table 9) was produced from diverse substrates using genetically engineered Pseudomonas strains. It is noted that the AG4074 strain has an exogenous nucleic acid comprising the itp1 gene (encoding an efflux pump for itaconic acid), and the AG4116 strain has an exogenous nucleic acid comprising the thrB gene (efflux pump for trans-aconitate).

TABLE 8 Production of Itaconic Acid from diverse substrates. Engineered strains were cultured on substrates encompassing a variety organic compound classes. Samples were collected following 72 hours growth and the final titer (g/L) of either itaconic acid or trans-aconitate was determined via HPLC. Genotypes of the engineered species are as follows:AG4001 AG4001:ΔPP_4740::Bxb1-attL:kanR:PT7:cadA:attR ΔampC::Pr_4841_T7_RNAP-lysY(+) ΔphaC1/Z/C2 icd(A1T):idh(A1T) Δged::araE-araCDABE fpvA:xylE-xylDXBC, AG4074:KT2440 ΔhsdR::Bxb1attL-KanR:Plac: itp1:Pt7:tad1:adi1-attR ΔampC::Pr_ 4841_T7_RNAP-lysY(+) ΔphaC1/Z/C2 icd(A1G):idh(A1G). Substrate (Concentration) Glucose Xylose Arabinose Coumarate Ferulate Benzoate Acetate Succinate Octanoate Glycerol Strain (20 mM) (20 mM) (20 mM) (20 mM) (20 mM) (20 mM) (30 mM) (30 mM) (15 mM) (40 mM) AG4001 0.970 0.359 0.475 N/A N/A N/A N/A N/A N/A N/A AG4074 NA N/A N/A 1.522 1.237 0.740 0.053 0.254 0.140 0.644 Sugar Non- Non- Aromatic Aromatic Aromatic Organic Organic Fatty Biodiesel native native Monomer Monomer through Acid Acid Acid Waste sugar sugar alternate pathway Substrate Class

TABLE 9 Production of Trans-aconitate from diverse substrates. Engineered strains were cultured on substrates encompassing a variety organic compound classes. Samples were collected following 72 hours growth and the final titer (g/L) of either itaconic acid or trans-aconitate was determined via HPLC. Genotypes of the engineered species are as follows:AG4003:ΔPP_4740::Bxb1-attL:kanR:PT7:adi1:attR ΔampC::Pr_4841_T7_RNAP-lysY(+) ΔphaC1/Z/C2 icd(A1T):idh(A1T) Δgcd::araE-araCDABE fpvA:xylE-xylDXBC, AG4116:KT2440 ΔhsdR::Bxb1attL-KanR:Plac: tbrB:Pt7:adi1-attR ΔampC::Pr_4841_T7_RNAP-lysY(+) ΔphaC1/Z/C2 icd(A1G):idh(A1G). Substrate (Concentration) Glucose Xylose Arabinose Coumarate Ferulate Benzoate Acetate Succinate Octanoate Glycerol Strain (20 mM) (20 mM) (20 mM) (20 mM) (20 mM) (20 mM) (30 mM) (30 mM) (15 mM) (40 mM) AG4003 0.0117 0.0128 0.0003 N/A N/A N/A N/A N/A N/A N/A AG4116 N/A N/A N/A 1.106 0.796 0.680 0.086 0.470 0.604 0.670 Sugar Non- Non- Aromatic Aromatic Aromatic Organic Organic Fatty Biodiesel native native Monomer Monomer through Acid Acid Acid Waste sugar sugar alternate pathway Substrate Class 

What is claimed is:
 1. A genetically-modified bacterium from the genus Pseudomonas comprising an exogenous nucleic acid encoding an enzyme that uses cis-aconitate as a substrate.
 2. The genetically-modified bacterium of claim 1, wherein the exogenous nucleic acid encodes a cis-aconitate decarboxylase.
 3. The genetically-modified bacterium of claim 1, wherein the exogenous nucleic acid encodes an aconitate isomerase.
 4. The genetically-modified bacterium of claim 3, wherein the bacterium further comprises an exogenous nucleic acid encoding a trans-aconitate decarboxylase.
 5. The genetically-modified bacterium of claim 3, wherein the bacterium does not have an exogenous nucleic acid encoding a trans-aconitate decarboxylase.
 6. The genetically-modified bacterium of claim 1, wherein the bacterium comprises an exogenous nucleic acid encoding a cis-aconitate decarboxylase, an exogenous nucleic acid encoding an aconitate isomerase, and an exogenous nucleic acid encoding a trans-aconitate decarboxylase.
 7. The genetically-modified bacterium of claim 1, wherein both the endogenous phaC1 gene and the endogenous phaC2 gene are inactivated in the bacterium.
 8. The genetically-modified bacterium of claim 1, wherein the bacterium is grown on lignin or a breakdown product of lignin as a carbon source.
 9. The genetically-modified bacterium of claim 1, wherein the breakdown product of lignin comprises p-coumaric acid, ferulic acid, or saccharides.
 10. The genetically-modified bacterium of claim 1, wherein the bacterium is grown on an organic compound selected from the group consisting of an aromatic compound, a saccharide, an organic acid, and an alcohol.
 11. The genetically-modified bacterium of claim 1, wherein the bacterium is grown on an organic compound selected from the group consisting glycerol, a diacid, a fatty acid, and benzoic acid.
 12. The genetically-modified bacterium of claim 1, wherein the bacterium further comprises an exogenous nucleic acid encoding a citrate synthase.
 13. The genetically-modified bacterium of claim 12, wherein the citrate synthase is a mutant enzyme that is immune to allosteric inhibition.
 14. The genetically-modified bacterium of claim 1, wherein the level of isocitrate dehydrogenase in the bacterium is reduced compared to a non-genetically modified bacterium.
 15. The genetically-modified bacterium of claim 14, wherein (i) the start codon of the isocitrate dehydrogenase gene is either “GTG” or “TTG,” (ii) the isocitrate dehydrogenase gene promoter comprises a mutation, (iii) the ribosome binding site of the isocitrate dehydrogenase gene transcript comprises a mutation, or (iv) the isocitrate dehydrogenase encoded by the isocitrate dehydrogenase gene comprises a protease recognition sequence.
 16. The genetically-modified bacterium of claim 1, wherein the bacterium is selected from the group consisting of P. aeruginosa, P. alcaligenes, P. anguilliseptica, P. argentinensis, P. borborid, P. citronellolis, P. flavescens, P. mendocina, P. nitroreducens, P. oleovorans, P. pseudoalcaligenes, P. resinovorans, P. straminea, P. asplenii, P. aurantiaca, P. aureofaciens, P. chlororaphis, P. corrugate, P. fragi, P. lundensis, P. taetrolens, P. Antarctica, P. azotoformans, P. blatchfordae, P. brassicacearum, P. brenneri, P. cedrina, P. corrugate, P. fluorescens, P. gessardii, P. libanensis, P. mandelii, P. marginalis, P. mediterranea, P. meridiana, P. migulae, P. mucidolens, P. orientalis, P. panacis, P. protegens, P. proteolytica, P. rhodesiae, P. synxantha, P. thivervalensis, P. tolaasii, P. veronii, P. denitrificans, P. pertucinogena, P. putida group, P. cremoricolorata, P. entomophila, P. fulva, P. monteilii, P. mosselii, P. oryzihabitans, P. parafulva P. plecoglossicida, P. putida, P. balearica, P. luteola, P. stutzeri, P. amygdali, P. avellanae, P. caricapapayae, P. cichorii, P. coronafaciens, P. ficuserectae, P. helianthin, P. meliae, P. savastanoi, P. syringae, P. tomato, P. viridiflava, P. abietaniphila, P. acidophila, P. agarici, P. alcaliphila, P. alkanolytica, P. amyloderamosa, P. asplenii, P. azotifigens, P. cannabina, P. coenobios, P. congelans, P. costantinii, P. cruciviae, P. delhiensis, P. excibis, P. extremorientalis, P. frederiksbergensis, P. fuscovaginae, P. gelidicola, P. grimontii, P. indica, P. jessenii, P. jinjuensis, P. kilonensis, P. knackmussii, P. koreensis, P. lini, P. lutea, P. moraviensis, P. otitidis, P. pachastrellae, P. palleroniana, P. papaveris, P. peli, P. perolens, P. poae, P. pohangensis, P. protegens, P. psychrophile, P. psychrotolerans, P. rathonis, P. reptilivora, P. resiniphila, P. rhizosphaerae, P. rubescens, P. salomonii, P. segitis, P. septica, P. simiae, P. suis, P. teessidea, P. thermotolerans, P. toyotomiensis, P. tremae, P. trivialis, P. turbinellae, P. tuticorinensis, P. umsongensis, P. vancouverensis, P. vranovensis, P. xanthomarina, P. taiwanensis.
 17. The genetically-modified bacterium of claim 1, wherein the bacterium further comprises an exogenous nucleic acid encoding an itaconic acid efflux pump.
 18. The genetically-modified bacterium of claim 5, wherein the bacterium further comprises an exogenous nucleic acid encoding a trans-aconitate efflux pump.
 19. A method for converting an organic compound to itaconic acid or trans-aconitate, the method comprising inoculating an aqueous solution containing said organic compound with a genetically-modified bacterium from the genus Pseudomonas, wherein the bacterium comprises an exogenous nucleic acid encoding an enzyme that uses cis-aconitate as a substrate.
 20. The method of claim 19, wherein the organic compound is selected from aromatic compounds, saccharides, organic acids, and alcohols.
 21. The method of claim 19, wherein the organic compound is a breakdown product of lignin produced during a lignin depolymerization process.
 22. The method of claim 19, wherein the organic compound is selected from the group consisting of aromatic compounds, glycerol, diacids, fatty acids, and benzoic acid.
 23. The method of claim 19, wherein the aqueous solution is a lignin depolymerization stream or derived from a lignin depolymerization stream.
 24. The method of claim 19, wherein the lignin depolymerization stream contains p-coumaric acid, ferulic acid, and saccharides.
 25. The method of claim 19, wherein the bacterium produces itaconate, and wherein the exogenous nucleic acid encodes a cis-aconitate decarboxylase.
 26. The method of claim 19, wherein the exogenous nucleic acid encodes an aconitate isomerase.
 27. The method of claim 26, wherein the bacterium produces itaconate, and wherein the bacterium further comprises an exogenous nucleic acid encoding a trans-aconitate decarboxylase.
 28. The method of claim 26, wherein the bacterium produces trans-itaconate, and wherein the bacterium does not have an exogenous nucleic acid encoding a trans-aconitate decarboxylase.
 29. The method of claim 19, wherein both the endogenous phaC1 gene and the endogenous phaC2 gene are inactivated in the bacterium.
 30. The method of claim 19, wherein the bacterium further comprises an exogenous nucleic acid encoding a citrate synthase.
 31. The method of claim 30, wherein the citrate synthase is a mutant enzyme that is immune to allosteric inhibition.
 32. The method of claim 19, wherein the level of isocitrate dehydrogenase in the bacterium is reduced compared to a non-genetically modified bacterium.
 33. The genetically-modified bacterium of claim 32, wherein (i) the start codon of the isocitrate dehydrogenase gene is either “GTG” or “TTG,” (ii) the isocitrate dehydrogenase gene promoter comprises a mutation, (iii) the ribosome binding site of the isocitrate dehydrogenase gene transcript comprises a mutation, or (iv) the isocitrate dehydrogenase encoded by the isocitrate dehydrogenase gene comprises a protease recognition sequence.
 34. The method of claim 19, wherein the bacterium is selected from the group consisting of P. aeruginosa, P. alcaligenes, P. anguilliseptica, P. argentinensis, P. borborid, P. citronellolis, P. flavescens, P. mendocina, P. nitroreducens, P. oleovorans, P. pseudoalcaligenes, P. resinovorans, P. straminea, P. asplenii, P. aurantiaca, P. aureofaciens, P. chlororaphis, P. corrugate, P. fragi, P. lundensis, P. taetrolens, P. Antarctica, P. azotoformans, P. blatchfordae, P. brassicacearum, P. brenneri, P. cedrina, P. corrugate, P. fluorescens, P. gessardii, P. libanensis, P. mandelii, P. marginalis, P. mediterranea, P. meridiana, P. migulae, P. mucidolens, P. orientalis, P. panacis, P. protegens, P. proteolytica, P. rhodesiae, P. synxantha, P. thivervalensis, P. tolaasii, P. veronii, P. denitrificans, P. pertucinogena, P. putida group, P. cremoricolorata, P. entomophila, P. fulva, P. monteilii, P. mosselii, P. oryzihabitans, P. parajidva, P. plecoglossicida, P. putida, P. balearica, P. luteola, P. stutzeri, P. amygdali, P. avellanae, P. caricapapayae, P. cichorii, P. coronafaciens, P. ficuserectae, P. helianthin, P. meliae, P. savastanoi, P. syringae, P. tomato, P. viridiflava, P. abietaniphila, P. acidophila, P. agarici, P. alcaliphila, P. alkanolytica, P. amyloderamosa, P. asplenii, P. azotifigens, P. cannabina, P. coenobios, P. congelans, P. costantinii, P. cruciviae, P. delhiensis, P. excibis, P. extremorientalis, P. frederiksbergensis, P. fuscovaginae, P. gelidicola, P. grimontii, P. indica, P. jessenii, P. jinjuensis, P. kilonensis, P. knackmussii, P. koreensis, P. lini, P. lutea, P. moraviensis, P. otitidis, P. pachastrellae, P. palleroniana, P. papaveris, P. peli, P. perolens, P. poae, P. pohangensis, P. protegens, P. psychrophile, P. psychrotolerans, P. rathonis, P. reptilivora, P. resiniphila, P. rhizosphaerae, P. rubescens, P. salomonii, P. segitis, P. septica, P. simiae, P. suis, P. teessidea, P. thermotolerans, P. toyotomiensis, P. tremae, P. trivialis, P. turbinellae, P. tuticorinensis, P. umsongensis, P. vancouverensis, P. vranovensis, P. xanthomarina, P. taiwanensis.
 35. The method of claim 19, wherein the bacterium further comprises an exogenous nucleic acid encoding an itaconic acid efflux pump.
 36. The method of claim 28, wherein the bacterium further comprises an exogenous nucleic acid encoding a trans-aconitate efflux pump. 